Moved the guts of psfex.py to the python directory
Adjust scaling for histogram plot
Got psfexStarSelector working
Dummy version of PsfexPsfDeterminer

N.b. implementation is identical to PcaPsfDeterminer
N.b. boost persistence is disabled (enabling it requires changes to afw)
Updated using bin/psfex -dd
Version to use with LSST stack

N.b. could/should be trimmed down to only use values we care about, or else
be replaced by a pex_config file.  The latter would make our python bindings
less generic.
Got psfex running in the lsst stack, but only by faking the final PsfexPsf class

I.e. the psfex code runs and generates a psf, but we don't map it into
a correct lsst Psf
We're using the "trace radius", not the "determinant radius"
Got the pipeline running using PsfexPsf.

N.b. PSF persistence is not done yet.
Started to clean up unused config parameters (but did not yet start replacing
the psfex configuration with pex_config)
Got (FITS-with-Exposure) persistence working
Removed (#ifdef'd out, unimplemented) boost::persistence code

Also renamed inclusion guards
We need to transpose the vignets (i.e. (x,y) v. (y, x) conventions)
Remember to free s_sample

Also formatting changes to match Emannuel's style
Use objectSize star selector
Add PsfexPsf::getkernel to allow the use of generic (meas_algorithms) diagnostic plots
A tiny step towards using pex_config; remove PSF_SIZE as it's set in the code