Some geometry transformations zoom out previews

[davidh]

Crop, Level, Warp and maybe some other transformations zoom out the previews of all the images downstream considerably.

[jsachs]

I am still working on this problem. It has something to do with the transformations being split screen and this zooms the input image out to fit, but it seems to be complicated when it happens and when it doesn't. While it's harmless, it is annoying and I would like to fix it once and for all.

[jsachs]

I think I have made some good progress on this, hopefully without breaking anything else. Should have a new version shortly.