Split support interface skip height in roof and bottom
Split support interface skip height in roof and bottom

You can now tune them differently.

Contributes to issue CURA-3491.

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