Move point to the beginning of BibTeX entry named KEY.
Return position of entry if KEY is found or nil if not found.
With GLOBAL non-nil, search KEY in `bibtex-files'. Otherwise the search
is limited to the current buffer. Optional arg START is buffer position
where the search starts. If it is nil, start search at beginning of buffer.
If DISPLAY is non-nil, display the buffer containing KEY.
Otherwise, use `set-buffer'.
When called interactively, START is nil, DISPLAY is t.
Also, GLOBAL is t if the current mode is not `bibtex-mode'
or `bibtex-search-entry-globally' is non-nil.
A prefix arg negates the value of `bibtex-search-entry-globally'.
(fn KEY &optional GLOBAL START DISPLAY)