German

Here it is the update of the strings.

A couple of notes:
  1. 7dbfb74838e94cf8e16a4e01dcb661c01b332990 have a look, should be fine, but better be sure,
  2. ```$txt['profile_warning_notify_template_outline_post']``` and ```$txt['profile_warning_notify_template_outline']``` in Profile.german.php were quite different compared to the ones in master, and probably broken. I tried to "fix" them, but the sentence changed, so it's probably still broken... :blush: 
  3. I found a couple of missing strings in Who.german.php:
```
$txt['whotopic_watch'] = 'Started watching a topic.';
$txt['whotopic_unwatch'] = 'Stopped watching a topic.';
```