Log Message:
Update converters/bibtex2html to 1.89

Version 1.89, 08/01/2008
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 o entry types and field names now typeset in lowercase in f_bib.html
 o new option -unicode to use Unicode entities for some macros
   (such as ◯ for \bigcirc, etc.)
 o new option -html-entities to use HTML entities for some macros
   such as \le, \approx, etc. (patch by Steven G. Johnson)
 o new option -header to insert a header (similar to -footer)
  (patch by Steven G. Johnson)