[input:bibtex] Fix unwrapping title values again
[input:bibtex] Fix unwrapping title values again

Fix unwrapping title values properly. Now, it
also checks for cases like these:

   {foo} bar baz {qux}

This doesn't count as a top-level tag, but would
be picked up like one before, and break the
parser besides being incorrect.

Note that title values technically shouldn't be
unwrapped, but are in both Biber and BBT (#155).

See d2798d6bebf0ef8ed564c2d28e4033b6b4887730
See #155

larsgw/citation.js,larsgw/citation.js