(bookmark-search-prompt, bookmark-search-timer): Remove.

(bookmark-search-prompt, bookmark-search-timer): Remove.
(bookmark-search-pattern): Move and leave unbound.
(bookmark-bmenu-mode-map): Change binding.
(bookmark-read-search-input): Simplify.
Don't use text-char-description.  Don't error on non-char events.
(bookmark-filtered-alist-by-regexp-only): Remove by folding into the
only caller (i.e. bookmark-bmenu-filter-alist-by-regexp).
(bookmark-bmenu-search): Don't check we're in a bookmark-list buffer.
Use a local var for the timer.
(bookmark-bmenu-cancel-search): Remove by folding into the only caller
(i.e. bookmark-bmenu-search).