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.
Merge branch 'follow-topics' of https://github.com/petrjasek/Newscoop into v4.1