Bug in vehicle MaskBits

The NextFreeMask definition should be the last one, i.e.:

enum MaskBits {
      PositionMask = Parent::NextFreeMask << 0,
      FrozenMask   = Parent::NextFreeMask << 1,
      EnergyMask   = Parent::NextFreeMask << 2,
      NextFreeMask = Parent::NextFreeMask << 3
   };

Otherwise you'll have problems if you create any more mask bit defs in Vehicle subclasses.