Xrayutilities

* fix issue 84: edge case problemes in XRDML parser
* matplotlib compatibility improvements

* issue 87: fix matplotlib inline backend in FitModel.fit
* enable parsing of Panalytical XRDML version >2.0
* issue 79: fix parsing of Sardana generated spec files; thanks to DS
* issue 81: fix parsing materials with space group 47
* packaging cleanup: remove gitignore and other dev-files
* issue 77: complete multiprocessing cleanup upon PowderModel.close()
* issue 76: cif parser: fix bug introduced in version 1.5.2

* fix bug in PowderDiffraction where the last Bragg peak before tt_cutoff was
omitted, thanks to NG for reporting the issue
* new model for calculating signal of mosaic small crystals
* add arbitrary line cut function
* fix parsing of empty scans in spec files
* remove geth5_map function -> use geth5_scan instead
* support inf/nan values in spec files
* setup.py fixes for Debian packaging
* CIF export: make _atom_site_label unique
* change of SMaterial.density to a unit of kg/m3
* deprecate the fit_xrr function, which will be remove in the next major
version -> use the new FitModel
* new FitModel class for fitting of instances of LayerModel
* fix bug in PowderDiffraction used with enable_simulation=False

* simple unit cell visualization function: Crystal.show_unitcell()
* add new 'radius' and 'color' properties to Elements
* improve testing of various unit cell settings in CIFFile
* fix bug in handling negative data in kill_spike, thanks to reihel for
reporting
* Panalytical XRDML: parse hkl from file if present
* CIF exporter and possibility to parse CIF files from string representations
* new reflectivity code based on transfer matrices (contributed by Numan
Laanait, nlaanaitgmail.com)
* unittest and code quality updates
* show_reciprocal_space_plane function to plot a cut in reciprocal space
together with the peak positionn of a given material
* new FourC experiment class, equivalent to HXRD, but using a four circle
goniometer for consistent Q2Ang and Ang2Q functions
* add spline coefficients to PowderModel fits
* allow single Layer object as argument in LayerModel
* rewrite of line cut functions, shorter code, faster execution, more
versatile
* avoid loops in Experiment.Q2Ang functions
* clean README and add new CONTRIBUTIONS instructions

* improved docstring formating
* simulation code for diffuse X-ray reflectivity
* more flexibility in defining materials Wyckoff positions
* convenience function to calculate diffracted intensities of thin films to
compare various Bragg peaks (coplanar diffraction geoemetry)
* simplify WyckoffBase of Alloy, by avoiding double entries
* CIF parser now is able to fully parse files without symmetry operations
* CIF parser now distinguishes multiple "_data" entries
* improvement of the scanning XRD dataset parsers for ID01 (FastScan)
* PEP8 improvements
* speed optimization in EDF parser
* add getheader_element to SPECScan
* try to parse oxidation state of elements from a CIF file, and ignore '.' and
'?' values for Debye-Waller factors and occupation
* numpy 1.14 related fixes (mostly in file parsers)
* fix bugs in spacegroups whos Wyckoff position contains a multiplication
* make U/UB matrix compatible with the definition in SPEC
* remove deprecated Lattice/LatticeBase code
* update XRR example

* introduce convenience function HKL to convert q-vectors to HKL of materials
* update outdated information and fix typos in README
* introduce abstract classes where useful
* code cleanup (import statements)
* vastly improved CIF file support with recognition of correct space group and
Wyckoff position
* use AppVeyor.com for Windows testing and binary creation
* make wavelength handling in PowderDiffraction more flexible
* fix bug in SiGe alloy class
* python2 fix for EDFFile which could have failed as described in issue 41
* fix clear_bit utility function
* fix float/int conversion in line cut functions for newer numpy