Log Message:
Update emacs-snapshot to 24.0.50.20101016.

Recent changes:
        * mail/rmail.el (rmail-show-message-1): Catch an error of
        base64-decode-region and just show an error message (bug#7165).
        * subr.el (last): Deal with dotted lists (reported in bug#7174).
        * subr.el (last): Use `safe-length' instead of `length' (bug#7206).
        * image.el (image-library-alist): Declare as obsolete alias.
        (image-type-available-p): Use `dynamic-library-alist'.
        * subr.el (last): Make it faster.  (Bug#7174)
        * cus-theme.el (custom-theme--listed-faces): Add cursor face.
        (describe-theme-1): Extract doc from unloaded themes.
        * cus-theme.el (describe-theme, customize-themes)
        (custom-theme-save): New commands.
        (custom-new-theme-mode-map): Bind C-x C-s.
        (custom-new-theme-mode): Use custom--initialize-widget-variables.
        (customize-create-theme): New optional arg THEME.
        (custom-theme-revert): Use it.
        (custom-theme-visit-theme): Remove dead code.
        (custom-theme-merge-theme): Use custom-available-themes.
        (custom-theme-write): Make interactive.
        (custom-theme-write): Use custom-theme-name-valid-p.
        (describe-theme-1, custom-theme-choose-revert)
        (custom-theme-checkbox-toggle, custom-theme-selections-toggle):
        New funs.
        (custom-theme-allow-multiple-selections): New option.
        (custom-theme-choose-mode): New major mode.
        * ibuffer.el (ibuffer-mode-map): Don't redefine the cursor keys,
        since that's too annoying.  Move the filter groups commands to
        TAB/backtab.