Add a game start dialog

[Henrik Heimbuerger]

After configuring the game in the player view, the user should be able to start a game using a toolbar button.

This should invoke a game start dialog that shows the game startup process in multiple phases. Depending on the game configuration, this might also require interaction with the user.

Which phases are required needs to be determined, but definitely comprises of:

1. Initialisation of input devices, for example Wiimotes have to be connected to the system if they haven't before.
2. Initialisation of the specific track controller, for example when using 42 for the first time (or maybe always?), the cars have to be given unique IDs.
3. Some kind of preparation phase, so all players are ready to start the race. This could f.e. be visualised with traffic lights.