Control object and interface for new shapelet-to-PSF fitting code
Modified PSF-fitting interface, model class for it
New interface for PSF-shapelet fitting nominally complete (still needs testing)
Improved Python wrappers, initial tests for PsfFitter
Add class docs for PsfFitter.
Add failing unit test for psfFitter.apply()
Make test executable
Fix indexing bug in PsfFitter::apply()
Operate on correctly-sized subarray views in MultiShapeletPsfLikelihood
Rework still-failing test for PSF fitting
Merge PsfFitter tests
Fix bug in PsfLikelihood evaluation
Switch from scipy.integrate.Inf to numpy.Inf for better scipy version compatibility
Modify test data filename to make it work with test; adjust tolerance accordingly
Remove obsolete comment in test code
Use PsfFitterPrior as originally intended

Setting nonzero priorSigma values in the config was supposed to case a prior
to be used, but I'd neglected to actually enable that.  Also changed a test
threshold to reflect the new behavior.
Add double overload of PsfFitter::apply for convenience
Add missing import, remove duplicate lines from PsfFitter test.
Add example to quickly fit multiple PSF postage stamps.
Swap order of PsfFitter arguments, add config-derived default