Update de_DE.lang

Some small fixes; also, a suggestion: Because of the mod's name e.g. "Energiestiefel" should just be called "Powerstiefel", maybe, because it fits better to the mod's name.

P.S.: I hope it is UTF-8-encoded, if it is not, I'll change the file.
Update de_DE.lang

Now with correct encoding!
Update de_DE.lang
Update de_DE.lang

UTF-8.
Merge pull request #370 from Vexatos/patch-1

Update de_DE.lang