Ncrystal

* Updates to CMake code which is needed to support creation of
NCrystal conda packages.
* ncrystal_inspectfile now has --version and --versionnum arguments.

* Introduce a new quick TextData factory for gas mixtures, supporting
on-the-fly gas mixtures through cfg-strings like
"gasmix::0.7xCO2+0.3xAr/2bar/30C". The format is rather flexible, and
supports both mass and molar fractions, relative humidity, and has an
alias for normal air ("gasmix::air"). See more details on the wiki:
https://github.com/mctools/ncrystal/wiki/Announcement-Release3.2.0
* Introduce NCMAT v7 which adds a new optional TEMPERATURE section to the
format, allowing the default temperature value to be modified from the
normal 293.15K, or even of locking the value at a certain value
(attempts at modifying it via cfg variables will then fail). This is
used by the new gasmix factory to error on the flawed but
correct-looking "gasmix::CO2/2bar;temp=200K" (which is not the same as
the correct "gasmix::CO2/2bar/200K"). Future developments might move the
gas mixture support to the NCMAT format itself (rather than just in the
pre-processing as now), which would solve the issue in a nicer way.
* At the C++ level, a new fmt_frac function allows easy printing of
floating point values which might be simple fractions, a dedicated
Pressure type was added, and a minor issue with confusing error messages
from NCMAT data from quick factories was addressed.

* Introduce cfg parameter named "ucnmode" which can be used to enable a
new dedicated modelling of UCN-production processes. Thus, appending
";comp=inelas;ucnmode=only" to a given cfg-string, will result in a
scattering process which ONLY contains UCN-production
events. Conversely, appending ";ucnmode=remove" will provide a process
which contains everything EXCEPT UCN-production events. This splitup is
intended to facilitate usage of biasing and variance reduction tricks
when designing VCN or UCN moderators. The UCN threshold defaults to
300neV, but this can of course be modified. In addition to just
facilitating a process splitup, the UCN-production process resulting
from "ucnmode=only" is more precise (essentially exact) than the usual
S(alpha,beta) treatment - which is rather precise in general, but
currently contains some flaws when sampling events where the neutron
loose almost all energy (see also next item).
* Improve general (i.e. also when not running with special ucnmode)
scattering-kernel based inelastic physics for the case where the neutron
looses almost all energy. Specifically, the sampling of S(alpha,beta)
near the kinematic endpoint is greatly improved. We still have
additional plans for how to completely remove any artifacts related to
the numerical processing, if manpower allows at some point in the
future.
* Add internal utilities for evaluating S(alpha,beta) kernels at any
(alpha,beta) point, and add utilities for what is essentially exact
sampling or integration for cross sections. These utilities are useful
as they allow us to validate scattering kernel models better, and are
used directly in the new UCN-production models.
* Add notice to the ncrystal_preparemcstasdir for how to make it work when
using NCrystal with the McStas-Union geometry system.
* CMake now actually installs the "nctool" alias of "ncrystal_inspectfile".
* S(alpha,beta) kernels hardcoded in .ncmat files will now have any
null-edges discarded upon loading. This is often needed for kernels
converted from ENDF files, where the alpha/beta grid is often larger
than needed.
* Add PiecewiseLinearFct1D utility class (for some reason we had utilities
for cubic splines and sampling of piece-wise linear functions, but not
for simple evaluations of them!).
* Fix bug when accessing DynInfo of directly specified scattering kernels
with the Python interface (the DI_ScatKnlDirect was missing a required
initialisation).
* The process summaries printed via ncrystal_inspectfile or accessed via
the Python interface, now supports multiple layers of nested
processes. This was required to support the new ExcludeUCNScatter
process, which is implemented as a wrapper of two other processes.
* Adding experimental and incomplete support for converting raw parsed
NCMAT data to JSON. This is intended to help avoid the need for
resorting to custom parsing code, but is clearly an expert-only feature
as the data is presented as-is, without additional loading.

* The NCrystal v3.0.0 release brings both major new features and technical
improvements "under the hood", with around 19.000 lines of code changed
in more than 300 files! The list of specific changes is too long to
document here, but the following bullet points mention a few highlights
as well as a select number of very specific technical details. For a
more detailed and hopefully readable overview, please refer to the
following page in the wiki:
https://github.com/mctools/ncrystal/wiki/Announcement-Release3.0.0
Furthermore, we would like to encourage users to post questions
concerning the new release (or anything else NCrystal related obviously)
to the forum at: https://github.com/mctools/ncrystal/discussions
* Support for multiphase materials. These can be defined in terms of phase
volume-fractions, either in cfg-strings
("phases<0.9*Al_sg225.ncmat&0.1*Be_sg.ncmat>"), in NCMAT data, or a
combination of those. All interfaces and tools have been updated to
properly integrate multiphase materials, in a manner which is believed
to not add complications when working with single-phase materials.
* Framework-level support for Small Angle Neutron Scattering (SANS)
physics. The release includes resources to facilitate future development
of advanced SANS models, and already include a hard-sphere SANS model
(useful both by itself, and as proof-of-concept for other models).
* Material densities can now be easily modified. This can be done by
either specifying a relative scaling,
"Polyethylene_CH2.ncmat;density=0.9x", or an absolute one:
"Polyethylene_CH2.ncmat;density=0.88gcm3" (g/cm^3) or
"Polyethylene_CH2.ncmat;density=0.1perAa3" (atoms/Aa^3).
* Support for quickly setting up unstructured materials with just a
cfg-string and without a data file for such simple materials. For
instance, a He3 gas might be defined via the cfg-string
"freegas::He/0.17kgm3/He_is_He3". This makes it easy to add materials
for which the structure is not deemed important (e.g. in a strong
absorber).
* The various new features can be combined for quickly settting up
advanced materials. For instance, here is how to define a low-density
polyethylene with enriched B4C pellets, even without a dedicated data
file for B4C:
"phases<0.99*Polyethylene_CH2.ncmat;density=0.8x&0.01*solid::B4C/2.5gcm3/B_is_0.95_B10_0.05_B11>"
* Improve documentation of cfg-string parameters, with the code now able
to provide dynamic documentation, which can be accessed either
programatically (with the Python/C/C++ API or by running
ncrystal_inspectfile --doc), or on the new wiki page:
https://github.com/mctools/ncrystal/wiki/CfgRefDoc
* Introduce for convenience a new cfg-string parameter "comp", which can
be used to easily pick out one or more of the components contributing to
the scattering cross section. For instance, appending ";comp=inelas" to
any cfg-string (i.e. "Al_sg225.ncmat;comp=inelas"), will disable all
components *except* inelastic models.
* Reflection (hkl) planes provided by NCrystal are now grouped according
to the symmetry-equivalency indicated by the space group. This has the
benefit of drastically improving both the initialisation time and memory
usage needed for hkl lists, and additionally makes it easier to use
reflection lists from NCrystal with other software which often depends
on such symmetry groupings. Additionally, ondemand loading for quicker
inspection (e.g. --dump will be almost instantaneous even for the most
complicated crystal structures), and by default only the 10 planes with
largest dspacing is shown.
* Improve and update McStas support:
- Make NCrystal work with both the McStas v2.7 and McStas v3.0 branches.
- Add ncrystal_ncmat2hkl cmd-line utility for converting NCMAT files to
the .laz and .lau files needed by the McStas PowderN and
Single_crystal components (note that this only includes Bragg
diffraction, not inelastic/incoherent/SANS/multiphase physics for
which direct NCrystal usage in the NCrystal_sample component or
McStas-Union system is needed).
- Utilities for better/easier integration between NCrystal and the
McStas-Union system for complex geometries.
* Remove the few optional files which were not copyrighted by the NCrystal
developers, ensuring that the entire NCrystal release now has a single
well-defined license (Apache 2.0). The removed files were used to
support the semi-obsolete .nxs file format, and will still be available
as a separately distributed plugin if really needed.
* Stop supporting Python 3.5. Oldest supported Python version is now
Python 3.6.
* Introduce NCMAT v6 which adds a new optional OTHERPHASES section to the
format, allowing secondary phases to be defined via volume fractions and
cfg-strings.
* Remove NCMatCfg::isPolyCrystal which used to return the opposite of
isSingleCrystal(). This was obviously misleading for non-crystalline
materials.
* Vector::normalise() now does nothing if the squared magnitude is already
within 2 ULP's of unity. This is to avoid repeated calls to this
function from inducing slight changes due to numerical inaccuracies in
the normalisation process.
* Add cyclical dependency detection in NCrystal factories to exit with
clear error instead of deadlocking. This is in particular needed to
handle cyclic dependencies in multiphase materials in which a phase is
wrongly defined by recursively referring back to the top level material.
* Type safe AtomData::captureXS in C++.
* Add utilities for encoding data in JSON format, which for now is used to
enable conversion of MatCfg objects as JSON objects. On the python side
this means that a cfg-string can be decoded into a Python dictionary
using the new decodeCfg function (a new encodeCfg function re-encodes
this into a cfg-string).
* Fix bug where scattering kernels generated on-the-fly from VDOS curves
with vdoslux values less than 3 (the default) were subsequently treated
to the "beta-thickening" procedure introduced in release v2.6.1. This
procedure is now, as intended, only applied to externally provided
kernels, since the on-the-fly generated ones already have an optimised
grid layout.
* ncrystal_inspectfile gets --energy/--liny/--logy/--xrange options to
control more aspects of the generated plots.
* Introduce an alias, nctool, for the ncrystal_inspectfile command (this
is done in anticipation of a future actual renaming of the command).
* Fix misleading ATOMDB examples in NCMAT documentation where cohSL
numbers for Si and Al were a factor of 10 off from realistic numbers,
which might confuse users to think they have to use a unit of 0.1fm
rather than fm for such numbers (github issue 77).

* Release candidate 3 for release 3.0.0.
* Detailed ChangeLog to come.

* Release candidate 2 for release 3.0.0.
* Detailed ChangeLog to come.