Bitmap animations are composed of a sequence of other visualizations.
This is all well and good until a visualization is deleted, at which
point all animations in all sets in the entire project have to be
checked and potentially changed, and perhaps even removed (if all of
the animation's members have been removed). This turns out to be
kind of annoying to deal with, but it's better to deal with it in
code than force the user to manually update broken animations.
This change adds thumbnails for the animations, currently generated
by offscreen composition. This approach doesn't work quite right.
The Visualization and Visualization Set editors are now fully
functional. You can create, edit, and rearrange sets, and they're
now stored in the project file.
Remove left/right arrow PNGs. Remove duplicate copies of icon.
Tweak some comments. Set application icon. Adjust padding on
group boxes in first tab of app settings.
