Rather huge changes in CVS - call to test

[David Philippi]

I've just changed the file endings of the level files from .xml to .plf
in order to allow the level files to be associated with Pingus. This
should make it much easier to test levels. I'd ask everyone to test
wheter I've missed a place or changed one to many.
I've also committed 8 new music files, level designers should try to
make some use of them. :-)

I'd also ask people to proofread translations, while testing wheter the
level changes worked I noticed a spelling error in a german description
and while correcting it I noticed two more in the same level
description. I should also mention that we could change the font for any
translation to iso-latin2 now and that the iso-latin1 one is complete.
Some translations chould profit from this "new" capabilities IIRC.

Bye David