Makefile: improve the help and add l10n related targets.
Makefile: improve the help and add l10n related targets.

Inspired from the !LodgeIt [http://dev.pocoo.org/projects/lodgeit/browser/Makefile Makefile].


git-svn-id: 0d96b0c1a6983ccc08b3732614f4d6bfcf9cbb42@9472 af82e41b-90c4-0310-8c96-b1721e28e2e2

rbaumg/trac,rbaumg/trac,rbaumg/trac,rbaumg/trac