Game 2: Improve operation of game

[Magalii]

There are probably some problems with the game-play or with the way the game works. This issue is meant to gather them so they can be fixed.

[Magalii]

It is possible to launch a ball before another one has fallen again. It shouldn't happen.

[Magalii]

The problem of being able to launch balls at wrong moments (while another one is moving or after the end of game) has been fixed.