New feature: variable room size (after split) - to change by instructor

Now instructors are capable of setting a specific room size (min 2,
max 6) before they launch the split.

Further optimizations to come.
Faster room information for students after split
Some forgotten variable removal
Fixing one small bug with students not seeing each other
Merge branch 'feature/variable_room_size' into develop
Moved old David's code to separate directory.

I'm archiving it for now, until I decide I don't need it anyway.
Saving it in unused directory is way faster than
1) switching branches
2) or reading code from the web
Merge branch 'release/v0.3.1'
Merge branch 'master' of github.com:pbanaszkiewicz/pitt