Add layer height role to profiles model
Add layer height role to profiles model

This layer height computation is rather complex, but because the items are now computed in a separate function, we can safely overwrite that and the update is made only once in the UI.

Contributes to issue CURA-2737.

ynotstartups/Wanhao,Curahelper/Cura,fieldOfView/Cura,ynotstartups/Wanhao,hmflash/Cura,fieldOfView/Cura,hmflash/Cura,Curahelper/Cura