Cleanup for etc/refcards/Makefile and related items

Cleanup for etc/refcards/Makefile and related items

* .bzrignore: Unignore etc/refcards/Makefile.

* make-dist: Do not distribute etc/refcards TeX intermediate files.

* Makefile.in (install-arch-indep):
Do not install etc/refcards TeX intermediate files.

* etc/refcards/Makefile: Rewrite to use portable Makefile syntax.
Add language-specific targets.
(distclean, extraclean): New rules.

*  etc/refcards/README: Add copyright and license.  Add Makefile details.
Mention http and FSF store versions.