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
fix npe

fix npe while importing grades
Merge remote-tracking branch 'origin/dev'
change calculation of displayed days

show menus for current day only until 4pm
fix npe

fix npe while parsing exams
fix npe

fix npe while accessing kusss
fix typo
Merge pull request #28 from marunjar/dev

merge latest changes
push version

push version to 0.22
Merge branch 'master' into new_ui