* Require language part of locale to be two lowercase letters.
* Update Makefile.doc comment -- add "include" comment.
* Get rid of muttator/locale/en-US/Makefile symlink in favor of include.
a.) Cleaned up copyright language to match conventions.
(I used the memoir document class documentation as a reference, but
these conventions are common throughout publishing)
* The (c) symbol has no legal meaning. Only the word "Copyright" and
an encircled lowercase c are appropriate. So the word "Copyright"
was placed before each (c).
* Each (C) was changed to (c).
* Kris uses the correct symbols in copyright notices, but those
symbols can be problematic in terminal-mode editors. Added the word
"Copyright" as well.
* Replaced colons/spaces after years with the word "by."
b.) Added a copyright notice to common/content/template.js. It was
missing one entirely. Please correct if it doesn't need one or if the
copyright isn't held by Martin.
c.) Also added a "tildetidy" target to Makefile common that includes a
version of the find line from the existing "clean" target (however,
this version uses "rm -fv" instead of "rm -f").
