Redraw times column on day change

This is necessary because the time of the first/last lecture may vary
between different days.
Extend Lecture class to remember whether lecture details have changed
Create lectureList class to provide list helper methods
check for changed lectures
Factor out loading of lectures into seperate method for reusing
Load/Store new lecture attributes from/to database
Scan for changes in lectures after parsing a new schedule
Add fragment to show schedule changes
Add Activity to display changes
Show list of lecture changes as Activity or Fragment
Show dialog indicating number of changed lectures on startup
show number of changed lectures in notification
refactor lecture member variables to camel case
Style adjustments for the lecture list

light theme, extra padding and header for side pane view
Merge branch 'list-changes-53'
Fix helper methods
Properly sort lectures across day boundaries

Most noticable in the list of changed lectured
Add new 31C3 build flavor, adjust URLs, change icons for 31C3