Qt: Update German GUI translation
Qt: Update German GUI translation

Some new strings added and a few strings polished.

Anty-Lemon/mgba,fr500/mgba,mgba-emu/mgba,mgba-emu/mgba,Iniquitatis/mgba,Iniquitatis/mgba,Anty-Lemon/mgba,mgba-emu/mgba,libretro/mgba,Iniquitatis/mgba,libretro/mgba,fr500/mgba,Anty-Lemon/mgba,libretro/mgba,fr500/mgba,libretro/mgba,mgba-emu/mgba,Anty-Lemon/mgba,Iniquitatis/mgba,libretro/mgba,fr500/mgba