Import Bibutils 6.6.
Expose NBIB output support.
Update to Bibutils 6.3.
Enable NBIB support.
Expose additional options values.
This is a patch release fixing MacOS X compilation.
Patched few minor warnings in imported Bibutils source.
Implemented Travis-CI builds through Cabal and Stack.
wordout_dropkey
because the corresponding
constant in Bibutils has also been removed.