Added cleanup tag to sandbox.py

Make it possible for user to save intermediate files
Removed -inf results from posterior PDF.

Plus two inconsequential edits.
Improved covariance matrix plotting.

No need to plot covariance between parameters that are held fixed.
Option to plot optical cutout

Can compare optical image with lens model results and observed data.
Auto-populate image.csh

Filename input/output, image size, and cell size can all be specified
automatically by visualutil.py and hence don’t need to be specified by
the user.
Functional CASA-uvmcmcfit

No more miriad dependency!!

Also, switched to .fits format for posteriorpdf.
Interactive cleaning is optional

Non-interactive cleaning is a bit faster.
Bugfix in visualutil.py
Convert to YAML configuration file format.
Bugfixes

Reflecting changes introduced with the adoption of config.yaml.
Preliminary attempt to merge CASA branch into master.
Accept CASA or uvfits files.

Also update visualutil.py to accommodate yaml configuration files.
Bugfix

Fits tables access column headers differently than hdf5 tables.
Better bug fix

Reading .fits table using astropy Table instead of fits.
Convert config.py to config.yaml

Plus other bug fixes.  Getting low acceptance fractions on XMM102.
Need to do additional debugging.
Testing.
Bugfix

Needed to normalize the chi^2 by the inverse variance.
More tests.
Bug was in old version of uvmcmcfit.py

I had been using [goodvis] to identify finite visibility measurements,
but goodvis was only applicable to the real visibilities, and hence
excluded the imaginary ones.
MPI Bugfix

EnsembleSampler was not setting up MPI pool correctly.