(reftex-view-crossref): Split up into several functions. No longer moves

(reftex-view-crossref): Split up into several functions.  No longer moves
to find a macro.
(reftex-view-cr-cite, reftex-view-cr-ref,
reftex-end-of-bib-entry): New functions.
(reftex-auto-view-crossref): New value `window' allowed.
(reftex-view-crossref-when-idle): Process new `window' option in
(reftex-translate-to-ascii-function): New default.
(reftex-label-illegal-re): Default changed, removed Latin1.
(reftex-latin1-to-ascii): New function.
(reftex-what-environment): Check for section regexp before use.
(reftex-find-tex-file, reftex-find-bib-file): Fixed bug with absolute
path names.
(reftex-TeX-master-file): Changed sequence of file checks.
(reftex-do-citation): bibview cache only with RefTeX mode on.