Free Hero Mesh

  Set by the game engine if the requested movement is diagonal.

bit20 *
  If set, then when the movement attempt is restarted (due to bit15 set),
  the direction will be reread from the object's Dir variable.

bit21 *
  Allows the object to move regardless of Height.
  Allows the object to move regardless of Height. The game engine sets
  this bit if currently the Climb/Height is OK for moving.

bit22 *
  Prevents movement regardless of Height, but may still allow sliding.

bit23 *
  Reserved for future.