Adds the MotorClusterState from the current SimulationState to the MassCalculation constructor. The ignition time of each motor is subtracted from the current simulationTime to calculate its current mass.
MassCalculation is also used for static analysis; in this case a synthetic time is passed (and there is no SimulationState). In this case, a null is passed in to the MassCalculation constructor; whether or not this the case is used to determine whether or not to calculate a motor time based on its ignition time.
Also clamp motorTime from MotorClusterState to be no less than 0 when calculating motor mass.
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