Update copyright notice to reflect assignment to FSF and incorporation

Update copyright notice to reflect assignment to FSF and incorporation
into Emacs.

Attempt to load `timer'.

(eldoc-idle-delay): Make defconst.
(eldoc-minor-mode-string): Make defconst.
(eldoc-argument-case): Make defconst.

(eldoc-message-commands): Renamed from eldoc-mode-message-commands.
All callers changed.
Add `mouse-set-point' as a default candidate.

(eldoc-use-idle-timer-p): New constant.
(eldoc-timer): New variable.
(eldoc-current-idle-delay): New variable.
(eldoc-schedule-timer): New function.
(eldoc-mode): Use idle timers if supported.

(eldoc-add-command): Provide completion on interactive commands only, not
all bound functions.

(eldoc-print-current-symbol-info): Renamed from
eldoc-mode-print-current-symbol-info.  All callers changed.
Check whether using idle timers or being run from post-command hooks.
Use `executing-kbd-macro' instead of `executing-macro'.

(eldoc-print-fnsym-args): Don't make interactive.
Cache current symbol name in eldoc-last-data; it was forgetting to do this
previously.
If subr args cannot be determined, show single-line docstring for it instead.

(eldoc-docstring-message): New function.
(eldoc-print-docstring): New function.
(eldoc-print-var-docstring): Use them.

(eldoc-function-argstring-from-docstring-method-table): New constant.
(eldoc-function-argstring-from-docstring): Use it.