Interactive Zoom Mouse Drag Direction

@jamesobutler,

I made the above changes. I simply swapped the zoom in/out Signals slots so that in calls out and out calls in. For instance…

The WidgetEventZoomInSlice (Zoom In) signal calls the opposite (Zoom Out) function, vtkMRMLSliceIntersectionWidget::WidgetEventZoomOutSlice, and visa versa.

This is obviously the wrong way to do it, right?

:expressionless: