(make-mode-line-mouse-sensitive): Add key

(make-mode-line-mouse-sensitive): Add key
definitions for `top-line'.
(mode-line-format): Replace `mode-name' with
`(:eval mode-line-mode-name)'.
(mode-line-mode-name): New.
(make-mode-line-mouse-sensitive): Don't change default value
of `mode-name'.
(make-mode-line-mouse-sensitive): Use down-mouse-3
instead of mouse-3 to pop up menus.
(make-mode-line-mouse-sensitive): Pop mouse buffer menu over
buffer name.
(mode-line-buffer-menu-1): Removed.
(mode-line-buffer-identification-keymap): New.
(mode-line-buffer-menu-keymap): New.
(mode-line-mode-menu-keymap): New.
(mode-line-unbury-buffer): New.
(mode-line-other-buffer): New.
(mode-line-buffer-menu-1): New.
(mode-line-mode-menu-1): New.
(make-mode-line-mouse-sensitive): New.