This topic introduces support for events in VTK to pass a
vtkEventData instance as their calldata. This instance can
be used to hold event specific data that would otherwise
complicate the render window interactor. The event specific
data also allows us to have fewer vtkCommands as we do not
need a specific command for each button on a controller but
rather can include the controller button as data in the
appropriate vtkEventData subclass.

Currently this is only implemented for 3D events but it could
be updated to handle mouse, keyboard or events as desired.