Re-implement the feature of showing eldoc info after editing.

Re-implement the feature of showing eldoc info after editing.

* emacs-lisp/eldoc.el (eldoc-post-insert-mode): Remove.
(eldoc-edit-message-commands): New function.
(eldoc-print-after-edit): New variable.
(eldoc-pre-command-refresh-echo-area): Emit message only by
eldoc-message-commands.
(eldoc-mode): Restrict eldoc-message-commands to editing commands
if eldoc-print-after-edit is set.

* progmodes/octave.el (octave-mode-menu): Adapt to change in
eldoc.

Fixes: debbugs:16346