Merge Changes into custom-server, mainly paint-functionality

See merge request !8

Added sounds & the ability to play them

See merge request !10

removed unnecessary tabs

fixed the random connection issues

See merge request !9

modify SkribblServer for FillOrder to work
make drawing possible in ..Canvas,
make drawing interface and Buttons in ..CanvasContainer by Esther

Some changes

See merge request !4

-did some cleaning up to the code of SkribblChat and wrote comments,
that part should now be Finished
-fixed the problem with the _isClose-method

-Now a message will be sent, when there is a new drawer and when a player
joins. It is planned that a message is also sent, when someone leaves,
but for that otherwhere some stuff has to be implemented first.
-fixed scrolling (again), but this time i really figured it out i think.
The soulution isnt the prettiest, but it works
-found a bug/problem with the isClose-Method

Merge branch 'custom-server' of https://gitlab.informatik.hu-berlin.de/eltschib/mathe-skribbl into some-changes