Functional uvmcmcfit with Gaussian priors.

Still needs testing to see if this implementation leads to reasonable
fits.
Normalize lnprior empirically.

For 2-sigma offset from expected parameter position, decrease lnprob by
10.  This value is empirically determined by examining the convergence
profile of a fit with uninformative priors on all parameters.
Work in progress.

Pausing development to fix a bug in uvutil.uvload when loading non-ALMA
data.
Testing normalization of 250.

A normalization of 25 was insufficient to pull down the lens for ADFS07
by any significant amount.  It may simply be that the 2MASS astrometry
is way off in this particular region of space.
Lnprior normalization is now 100.

250 was much too strong.
Dialing the normalization back to 2.5

The 2MASS astrometry appears to be uncertain at the ~0.5” level in an
absolute sense, so there is little point in placing Gaussian priors on
the source positions.
Bugfix when reinitializing uvmcmcfit.

pzero should only be initialized from paramSetup when no existing
posteriorpdf.hdf5 data are available.
Bugfix related to fixing parameters.

Can now “daisy-chain” two parameters together.  Might need to add a
recursive function to daisy chain N parameters together.  Will look
into this if necessary.
Bugfix in visualutil.py

Models without any lensing were not treated properly.
Added sandbox.py and bug fixes.

Sandbox offers quick inspection of a given set of model parameters.
You can adjust any parameter and quickly see how the interferometric
observation responds.

Also corrected a bug in how lists were parsed by setuputil.py
Merge branch 'gaussianpriors'
A number of improvements in gaussianpriors branch need to be merged into master.  Especially the sandbox tool.