Fix mouse wheel zooming in PyQt interactor
Fix mouse wheel zooming in PyQt interactor

* Use angleDelta() if delta() does not exist (PyQt5)
* Only zoom if cumulative delta is greater/less than +/- 15 degrees

keithroe/vtkoptix,sumedhasingla/VTK,keithroe/vtkoptix,sumedhasingla/VTK,sumedhasingla/VTK,SimVascular/VTK,keithroe/vtkoptix,SimVascular/VTK,SimVascular/VTK,sumedhasingla/VTK,SimVascular/VTK,SimVascular/VTK,SimVascular/VTK,sumedhasingla/VTK,keithroe/vtkoptix,SimVascular/VTK,keithroe/vtkoptix,SimVascular/VTK,keithroe/vtkoptix,sumedhasingla/VTK,sumedhasingla/VTK,keithroe/vtkoptix,keithroe/vtkoptix,sumedhasingla/VTK