Update currentSpeed in writeZHopStart() and writeZHopEnd().
Update currentSpeed in writeZHopStart() and writeZHopEnd().

It wasn't being updated and so the Z feedrate used was subsequently used for X/Y moves.

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