Make more members of InsetOrderOptimizer class const.
Make more members of InsetOrderOptimizer class const.

alephobjects/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,ROBO3D/CuraEngine