Rework count-words-region. New command count-words.

Rework count-words-region.  New command count-words.

See discussion at http://lists.gnu.org/archive/html/emacs-devel/2011-10/msg00193.html

* lisp/simple.el (count-words-region): Always count in the region.
Report the number of lines and characters too.
(count-words): New command, which counts in the buffer if the
region is inactive, as count-words-region used to.
(count-words--message): New function.  Handle plurals.
(count-lines-region): Make it an alias for count-words-region.

* lisp/bindings.el (esc-map): Replace count-lines-region with
count-words-region.

* doc/emacs/basic.texi (Position Info): Omit page commands.  Document
count-words-region and count-words.

* doc/emacs/text.texi (Pages): Move what-page documentation here.