Simplify the vector rotation.
Simplify the vector rotation.

We don't need two matrices, just one. So now we just do bb_middle + vec and
bb_middle - vec to get the same results as before.

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