The state of the shift modifier is now distributed across the
network. Walking speeds and animation states are being updated
according to it.
Fixes#130
In order to not provide deep exposure to PlayerController,
we refactored it so that it is not visible anymore outside Player.
Also we renamed isInBetweenGames to inBetweenRounds.
Moved creation of PlayerController from GameController(s) to
The channel Player and client Me.