Some outline for the database made, not yet functional
Merge remote-tracking branch 'original/master'
Implemented databases for mensas (menus not done yet). Faving a mensa now
correctly sets it as a favorite and stores this locally (this session
only; the data is overwritten after a restart. I will change this next)
Merge pull request #38 from NicolasKessler/master

Started with local database / implemented faving of mensas in the gui (see comment for details....)