Rm-tools

-QU-fitting updates from Alec Thomson: sigma-clipping of posteriors,
saving evidence to output file, option to not restart from scratch.
-Fixed bug in chunk reassembly script (assemble_chunks.py) where it would
not figure out the cube size correctly when fed the last chunk.
-Updated RMclean1D to use new derotated angle equation for Observed noise
(previously was using old flawed equation fixed in v1.0.2).
-Fixed problem with handling of degenerate FITS axes in RMclean3D
-Created new tool: RMpeakfit_3D.py,which applies the 1D peak fitting to
each pixel in a 3D FDF cube. Outputs 2D maps for the resulting
parameters.
-New Stokes I fitting. Two changes:
1) Logarithmic polynomial fitting function added. This is essentially
a 5-th order polynomial in log-log space, modified into the
standard power-law with curvature formulation. Added flags to
RMsynth1D, do_QUfitting, and do_fitIcube to let user select fitting
function.
2) Dynamic order selection. If user enters a negative polynomial order,
it will now trying fitting successively higher order polynomials
(starting with 0) until the AIC no longer improves.
-default Stokes I fitting is now 2nd order polynomial
-Plotting code has been made more consistent, in terms of no longer
requiring user to press 'Enter', for all routines.
-QUfitting now has .dat output like that of RMsynth1D.
-All supporting tools now have command-line hooks, which all begin with
'rmtools_'.

-Theoretical estimate for FWHM now uses formula from Dickey et al 2019
instead of Brentjens & de Bruyn 2005, as this is more accurate.
-RMSF fitting improved to be more accurate (previously would over-estimate)
-fitReal option for RMSF fitting now works as intended (previously crashed)

-Minor QUfitting fixes by Alec Thomson.
-Fixed crash when writing 3D cubes where all pixels are NaNs.
-changed output names for the QUfitting multinest files.
-Fixed crashes in RMsynth3D when input cubes are all NaNs.
-Fixed crash when RMsynth3D normalizes output cubes by Stokes I model.

-Minor fixes to new plot-saving code.
-Changed theoretical noise estimation equation: Shinsuke Ideguchi pointed
out that it wasn't correctly computing the error in the fractional
polarization. Modified to normalize the channel errors by the model
Stokes I (errors in the model are not accounted for). This will alter
the noise behaviour for sources with steep Stokes I spectra.

-RMsynth1D: added option to save plots (pull request by Lenart Heino)
-Error formula for the derotated polarization angle (dPolAngle0Fit/Chan)
was wrong (too small by a factor of sqrt(Nchan)). Corrected formula
incorporated.
-Multi-modal posterior handling added to QU-fitting (by Alec Thomson).

-For RMsynth1D, the default Phimax value was previously fixed at 600,
which was not ideal for high-frequency data. Modified to now be
dynamic: 10x RMSF FWHM.
-RMclean1D was not using the noise properly when calculating derived
properties. RMclean1D error bars prior to this verison likely have
issues.