Improving ScreenCenter/CenterBoundary logic

[Cheesebaron]

Hey Ondrej

Love your work here. However, I have a few suggestions for improvement.

When setting ScreenCenter and CenterBoundary on the Scene it is very hard to pan if either edge is at the center boundary. Would be nice if this somehow could improve where you are still allowed to pan, but it would maybe snap back to the CenterBoundary when you release when it is over-scrolled.

Also, if I zoom. Then the CenterBoundary isn't scaled up. Meaning panning after zooming may be impossible.

[AlisiaNew]

I also faced the issue when the CenterBoundary doesn't scale up and this affects it's 'bounding' possibilities: my scene can be panned outside of the visible area. I haven't found a workaround or a fix for this yet, would really appreciate if you could point in the right direction on this. Thanks!