Use modern import method
Use modern import method

This is more robust to cyclic dependencies, and also the intended way of importing these classes in Python in general.

Contributes to issues CURA-1278 and CURA-351.

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