Three small changes (copyright, template.js copyright, and tildetidy target)

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").

common/Makefile.doc

@@ -24,7 +24,7 @@ AWK           = awk
 
 #### rules
 
-.PHONY: all help doc asciidoc check-asciidoc clean distclean
+.PHONY: all help doc asciidoc check-asciidoc clean distclean tildetidy
 all: doc
 
 doc: asciidoc t2t
@@ -47,6 +47,10 @@ distclean: clean
 	@echo "More cleanup..."
 	rm -f $(DOC_FILES)
 
+tildetidy:
+	@echo "Removing vim backup files..."
+	find . -name '*~' -exec rm -fv {} \;
+
 #### Makes single-file makes easier to type
 
 %: %.html %.t2t %.xhtml %.t2t ;