Add framerate to additional scrollwheel event handlers

Needed additional framerate restrictions to handle touchpads that translate gestures into scrollwheel events at a too high rate

v0.8.4-beta2: When zooming, treat the range as a transformed range

This allows us to do things like allowing only zooming into 1 order of
magnitude  on a logarithmic scale

Better paning on non-linear axes

Pan limits on non-linear axes work better

Better panning on axes with non-linear transformations

v0.8.3

Update version number to 0.8.3 final.