Added german translations from on 4.5 and fixed some typos

Hi guys

Finally found some spare time to update the german translations. Thanks and keep on with the great work!

Griz

P.s: Would it be possible to start the (already helping) comments with the version number instead of the action (e.g. added in 4.5.1 --> 4.5.1 Added). In that way it would be a little easier to find all strings to translate (independent of them being added, edited oder whatever...)