Remove unused import
Remove unused import

This is only for debugging purposes, so it shouldn't have been included in the source code.

Fixes #585.

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