New post-self-insert-hook.

New post-self-insert-hook.
* src/cmds.c (Vself_insert_face, Vself_insert_face_command): Remove.
(Qpost_self_insert_hook, Vpost_self_insert_hook): New vars.
(internal_self_insert): Run post-self-insert-hook rather than handle
self-insert-face.
(syms_of_cmds): Initialize the new vars.
* lisp/facemenu.el (facemenu-self-insert-data): New var.
(facemenu-post-self-insert-function, facemenu-set-self-insert-face): New funs.
(facemenu-add-face): Use them.