Snapped-together layers get permanently stuck together and unmoveable while snapping is enabled

[Keavon]

This is a recent regression.

In this video, there also appears to be another regression I also discovered while recording this which is that rectangles don't snap together when translated with the Select tool when they overlap edges, however when scaled it does work.

snapping_regression.mp4

I've disabled snapping by default in a17ed68 as a mitigation for this high-severity bug. It should be reenabled by reverting the change to the snapping_enabled field in misc.rs and in the five demo art files.