Improve handling of .bib files

This adds support to place .bib files in arbitrary subdirectories of
your project directory. All files will be symlinked, or copied if
symlinking is not supported, to the temporary build directory.
This only works when using the map \b to run biblatex, for some reason
:Bibtex does not work. And you will have to add "bib" to g:atp_keep.
Add support for the glossaries package.

This calls makeglossaries if needed. Add "acn", "acr", "gls", "glsdefs",
"glo" and "ist" to g:atp_keep.
TODO: send feedback about the makeglossaries run back to vi.