(speedbar-edit-line, speedbar-buffer-kill-buffer,

(speedbar-edit-line, speedbar-buffer-kill-buffer,
speedbar-buffer-revert-buffer): Updated buffer finding regex to
handle the [?] tag.
(speedbar-find-selected-file): New function.
(speedbar-clear-current-file): Uses `speedbar-find-selected-file'
(speedbar-update-current-file): Uses `speedbar-find-selected-file',
and now `speedbar-last-selected-file' is defined as the path name
to the file, not just the file itself.
(speedbar-center-buffer-smartly): Fixed center error to handle
the whole buffer.
(speedbar-delete-subblock): Rewrote to be more robust, less clever.
(speedbar-timer-fn): Removed short display time for messages.