Import bibtex2html from pkgsrc-wip.

Import bibtex2html from pkgsrc-wip.

bibtex2html is a collection of tools for translating from BibTeX to
HTML.  They allow to produce, from a set of bibliography files in
BibTeX format, a bibliography in HTML format. Here are some features:

 o Handle any BibTeX style (even those producing multiple bibliographies);
 o Use additional fields like abstract, url, ps, etc. to insert web links;
 o Crossrefs are also replaced by links;
 o Sort by dates or authors, in increasing or decreasing order;
 o Read simple macros in TeX or LaTeX files;
 o Show syntax errors in BibTeX files;
 o Extract from one or several BibTeX files the set of entries satisfying a
   given criterion.