Make speed_layer_0 and cousin settings not per-mesh
Make speed_layer_0 and cousin settings not per-mesh

Fixed up some of the settable_per stuff.

Contributes to issue CURA-1507.

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