Controller

Controller is an object that controls Motors, Thrusters and others, which are connected to it. It is often essential for Planes and Ships.

Its appearance consists of signs and buttons which let players control:
 * A Yellow Text Label displays on the speed of connected propulsion objects, or part-spinning objects like Motor
 * Plus Button: Clicking on it will increase connected objects' speed
 * Negative Button: Opposite to a plus button, clicking on it will decrease connected objects' speed
 * Reverse Button: Clicking on it will reverse the objects' speed.
 * Full Stop Button: Clicking on it will set connected objects' speed into zero, which stops them from functioning.