(bookmark-write): Add numbered backups for bookmark file.

(bookmark-write): Add numbered backups for bookmark file.
(bookmark-version-control): New variable.

(bookmark-jump): bookmark-jump now gives a
default value if no bookmark is entered manually.
(bookmark-set): Default to bookmark-current-bookmark or
buffer-name the way bookmark-jump does.

(ctl-x-map): Check if C-x r is a prefix before using it as one.

Include string "Bookmarks" in defining
[menu-bar bookmark] in global-map in the menu-bar code.

(menu-bar-bookmark-map): Supply t as 4th arg of autoload.

(bookmark-jump-noselect): New subroutine taken from
bookmark-jump.  Support compressed files.
(bookmark-jump): Call bookmark-jump-noselect.
Offer to relocate if necessary, but change default dir to that of
the old bookmark in read-file-name.

(bookmark-set, bookmark-rename, bookmark-delete,
bookmark-write-file, bookmark-load, Bookmark-menu-show-filenames,
Bookmark-menu-hide-filenames, Bookmark-menu-bookmark,
Bookmark-menu-save, Bookmark-menu-load): Fixed the save-excursion
bugs by wrapping things in save-window-excursion as well.

(bookmark-make-menu-bar-alist): Added sorting.

(bookmark-map): Added new keybindings.
(bookmark-try-default-file): Set bookmarks-already-loaded to t after the load.

(list-bookmarks): Added bookmark menu stuff.
(Bookmark-menu-*): New functions.