Merge pull request #27 from marunjar/dev

pull Dev branch into master
fix npe

fix npe while loading exams
group menus by day

fix creation of tabs
push version

push version to 0.20
change exception handling
push version

push version to 0.21
Merge remote-tracking branch 'origin/dev'
Merge pull request #28 from marunjar/dev

merge latest changes
push version

push version to 0.22