previous background/next background

[scottporter]

See http://scratch.mit.edu/projects/41703948/

If you use the change background to previous background or change background to next background from an object other than the stage/background, Snapin8r does something interesting. It translates it as a change costume block for the current object, not the stage. I don't know that the correct behavior is supported in Snap, so not sure what Snapin8r should do... but I'm just documenting the issue.