(bibtex-hs-forward-sexp): Added to support

(bibtex-hs-forward-sexp): Added to support
using the hideshow package.
(hs-special-modes-alist): Added entry for bibtex to allow the use
of the hideshow package.
(bibtex-hide-entry-bodies): Deleted as hiding of entry bodies is
not longer provided by bibtex.el directly.  Instead the hideshow
package should be used.
(bibtex-mode-map, bibtex-edit-menu, bibtex-mode): Delete
references to bibtex-hide-entry-bodies.

Copyright notice is up to date.  Moved
maintainer information closer to the beginning of the bibtex.el
file.
(bibtex-maintainer-salutation): New constant.
bibtex-version): New constant.
bibtex-submit-bug-report): Use bibtex-version and
bibtex-maintainer-salutation.
(bibtex-entry-field-alist): Made booktitle field optional for
@inproceedings entries when crossreferenced.
(bibtex-entry-field-alist): Added booktitle field to proceedings
entry type (for cross referencing). Thanks to Wagner Toledo Correa
for the suggestion.
(bibtex-string-file-path): Fixed typo.
(bibtex-mode-map): Reserved the key `C-c &'
for reftex.el.
(bibtex-edit-menu): Added `reftex-view-crossref-from-bibtex'
to menu.