Update de_DE.ini

- Remove obsolete lines
- Remove duplicate/triplicate lines
- Keep translations consistent between GUI / DesktopUI
- Resolved some Sie/Du conflicts
- Removed superfluous hyphens
- Translated some not or barely translated lines
- Updated with changed / new lines from en_US
- Matched layout to the en_US template again
Merge pull request #196 from Krude/patch-1

Update de_DE.ini