Remove unneeded % escape sequence in german translation.

After 0.18 we need to have a proper fix for the original string as well.
Merge pull request #530 from stefanbeller/de

Remove unneeded % escape sequence in german translation.
Temporary fix for '%%' typo in speed bonus

Basically, provide a minimal English-to-English translation to correct it.
Merge pull request #531 from dorkster/bugfixes

Temporary fix for '%%' typo in speed bonus