Implement renaming of inactive user.

Once user is deleted his username can't be reused.
After renaming that won't be a problem anymore.
Add list_user_topics template block.
MOTM-151: Implement Meine Themen

Refactor follow topics action.
Add test if user is set to smarty block list_user_topics.
Fix user topic language handling.
Move upgrade script to proper destination.
Update proxies.
MOTM-351: Featured Article List isn't working in Article Editor

Fix date formating.
Merge branch 'follow-topics' of https://github.com/petrjasek/Newscoop into v4.1
Merge branch 'rename-inactive-user' of https://github.com/petrjasek/Newscoop into v4.1
Merge branch 'fix-article-playlist-edit' of https://github.com/petrjasek/Newscoop into v4.1
Merge branch 'v4.1' into zplus