Update Keymaps chapter of Lisp manual.

Update Keymaps chapter of Lisp manual.

* doc/emacs/keymaps.texi (Format of Keymaps): The CACHE component of keymaps
was removed on 2009-09-10.  Update lisp-mode-map example.
(Inheritance and Keymaps): Minor clarification.
(Searching Keymaps): Remove out-of-place enumeration.
(Key Lookup): Remove unnecessary example (one was already given in
Format of Keymaps).
(Changing Key Bindings): Update suppress-keymap example.
(Menu Bar, Tool Bar): Copyedits.
(Tool Bar): Update tool-bar-map example.