Merge pull request #1 from PaulPrice/building

Changes to build
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).
Add option to control whether psfex re-centroids candidates (default: no)
Fixed compilation warning