Marking participants of activities present/not present

[tomudding]

What would you like?

Functionality that allows organisers of an activity to mark participants of their activity as present/not present.

Why is this needed?

C4 has asked for this to make their work easier for lunch lectures. This functionality can also be useful for other organs in the association, so it must be available to all.

Other information

I think marking someone present should only be possible from 30 minutes before the activity starts to 30 minutes after the activity has ended. There is no point in marking someone present/not present outside this window (perhaps up to an hour after but not more to prevent abuse - maybe it is should use TimestampableTrait?).