ups: add build file.
doc: fix doc building
gitignore: add TAGS
psfexAdaptors: fix scribbling for size differences

The prefs weren't properly scribbled on, since sets.size() may be
different from prefs.ncat, resulting in segfault.

Also put scribbling into an RAII struct to remove code duplication
(in the catch and outside).
Revert "psfexAdaptors: fix scribbling for size differences"

This reverts commit 0a3779ede798bb8a4fb74986a49b6dd404bda08b.

Reverting commit pushed upstream.
Merge branch 'github'
Merge remote-tracking branch 'github-upstream/master'
Merge remote-tracking branch 'github-upstream/master'
PsfexPsfDeterminer: ignore sources with negative fluxes
PsfexPsfDeterminer: be more careful about source fluxes

A NAN source flux kills PSFEx (resultant PSF is composed entirely
of NANs), so catch that case, and any case where the flux
measurement is suspect.

Also catch the case that all samples were rejected and produce an
intelligible exception.