Made lispfiles translatable. This time the translations are stored externally

Made lispfiles translatable. This time the translations are stored externally
in .po files in the same directory as the lisp files. So you can have
translation files for complete level subsets now.

Because Ricardo added a hacked solution before and because people already used
that, someone has to go over all the maps now, extract the translations and put
them into separate files, I'm too lazy to do that now, I just translated some
files for testing.
Translation-Patches are always welcome ;-)

SVN-Revision: 2236