Added missing data files to cabal.
Removed commented out section.
bibtex.hs:  Make url field a MetaString to avoid escaping.

In particular, avoid escaping # as \#.
bibtex.hs: Fixed bug in given name resolution with commas.
Moved instance definitions to Reference, avoiding orhpans in Pandoc.
Removed unneeded import.
bibtex.hs: Handle field names with uppercase.
Rename bibtex.hs -> bibtex2yaml.hs.
Code clarify change.
bibtex2yaml:  fixed bug.
bibtex2yaml: Added basic option/argument parsing.
Rename bibtex2yaml.hs -> bibtex2pandoc.hs.
Made code easier to read.
bibtex2pandoc:  Added bibtex types, parse non-dropping-particle.
bibtex2pandoc: Omit non-dropping-particle field if not used.