Remove unnecessary parallel line collision detection
Remove unnecessary parallel line collision detection

Now that a collision is also triggered when the line crosses an endpoint of another line, the detection of collisions when the two lines are parallel is no longer needed.

Contributes to issue CURA-286.
totalretribution/CuraEngine,totalretribution/CuraEngine,alephobjects/CuraEngine,markwal/CuraEngine,ROBO3D/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,pratikshashroff/pcura,markwal/CuraEngine,markwal/CuraEngine,alephobjects/CuraEngine,pratikshashroff/pcura,ROBO3D/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,pratikshashroff/pcura,totalretribution/CuraEngine