fixes #47, made drifting framerate independent
fixes #47, made drifting framerate independent

MaxReimann/Troen,philippotto/GP2013,philippotto/GP2013,MaxReimann/Troen,MaxReimann/troen-simulator,philippotto/GP2013,MaxReimann/troen-simulator,MaxReimann/Troen,philippotto/GP2013,MaxReimann/troen-simulator,philippotto/GP2013,MaxReimann/Troen