(bookmark-completing-read): Use a popup menu if activated from the mouse.

(bookmark-completing-read): Use a popup menu if activated from the mouse.
Return a string, instead of a list of one string.
(bookmark-edit-annotation): Remove unused vars.
(bookmark-jump, bookmark-relocate, bookmark-insert-location)
(bookmark-rename, bookmark-insert, bookmark-delete): Adjust calls
to bookmark-completing-read.
(bookmark-bmenu-show-filenames, bookmark-bmenu-hide-filenames)
(bookmark-bmenu-mark, bookmark-bmenu-select, bookmark-bmenu-unmark)
(bookmark-bmenu-delete, bookmark-bmenu-list): Use inhibit-read-only
and erase-buffer.
(bookmark-menu-delete, bookmark-menu-rename, bookmark-menu-locate)
(bookmark-menu-jump, bookmark-menu-insert)
(bookmark-popup-menu-and-apply-function)
(bookmark-menu-popup-paned-bookmark-menu): Remove.
(bookmark-menu-build-paned-menu): Remove by folding it into
bookmark-menu-popup-paned-menu.
(menu-bar-bookmark-map): Move the define-key statements here.
Use the "non-menu" commands since they now pop up a menu if needed.
(bookmark-exit-hook-internal): Simplify.