LuaSyncedRead: extend arguments to Spring.TestMoveOrder
  old signature: TestMoveOrder(
    number unitDefID,
    number pos.x, number pos.y, number pos.z
  ) --> boolean
  new signature: TestMoveOrder(
      number unitDefID,
      number pos.x, number pos.y, number pos.z
      [, number dir.x
      [, number dir.y
      [, number dir.z
      [, boolean testTerrain
      [, boolean testObjects
      [, boolean centerOnly
      ]]]]]]
  ) --> boolean