(bookmark-load): Use `bookmark-import-new-list' to

(bookmark-load): Use `bookmark-import-new-list' to
load the new list carefully, renaming bookmarks as necessary.
In docstring, mention new renaming behavior.
Optional arg OVERWRITE replaces inaccurately-named REVERT.
If file loaded was bookmark-default-file, then set
bookmarks-already-loaded to t.
(bookmark-import-new-list): New func.
(bookmark-maybe-rename): New func, helper to above.
(bookmark-set-name): Accept bookmark as either string (behaves
same as before) or list (treat it as a bookmark record).

(bookmark-set, bookmark-maybe-load-default-file)
(bookmark-jump-noselect, bookmark-rename)
(bookmark-show-annotation): Discard pointless `progn's.

(bookmark-bmenu-mark, bookmark-bmenu-unmark)
(bookmark-bmenu-backup-unmark, bookmark-bmenu-delete-backwards):
Renormalize position after all else is done.

(bookmark-edit-annotation-mode, bookmark-bmenu-list)
(bookmark-show-annotation, bookmark-show-all-annotations):
Use `x' instead of `(not (eq x nil))'.

(bookmark-yank-word): Inner save-excursion changed to progn.
(bookmark-send-annotation, bookmark-send-edited-annotation)
(bookmark-insert): Use buffer-string instead of buffer-substring.
(bookmark-make-cell): Make sure annotation and info-node strings
contain no text properties.
(bookmark-relocate): Remember to rebuild bmenu buffer after a
bookmark has been relocated.
(bookmark-bmenu-check-position): Return a meaningful value --
callers have apparently been assuming this anyway.
(bookmark-build-xemacs-menu): Unused function deleted.
(bookmark-version): Removed this variable; the Emacs version suffices.