Don't hog the CPU when waiting for the game to start.

Subversion-branch: /branches/v2-branch
Subversion-revision: 2587
Handle client disconnects when waiting for the game to start. Abort game
startup if a player disconnects, or continue gracefully if a drone
disconnects.

Subversion-branch: /branches/v2-branch
Subversion-revision: 2588
Increase netgame timeout to 30 seconds.

Subversion-branch: /branches/v2-branch
Subversion-revision: 2589