Instead of crashing with a CommandError, now a non-writable location
of mo files will only make compilemessages complain and continue.
Thanks Ramiro Morales for the review.
Removed multiple locales separated by commas variation (that wasn't
working as documented) in favor of simply allowing use of the
``--locale``/``-l`` options more than once for ``makemessages`` and
``compilemessages``.
Thanks Romain Beylerian for the report and Claude, Simon for their help.
8750296918 from stable/1.6.x.
Claude Paroz
Aymeric Augustin
Ramiro Morales