Misaligned bounds handles in 2018.3 prefabs

[nukeandbeans]

Creating a prefab of a CSGModel and then trying to edit its brushes in the prefab editor keeps the visible handles aligned, but their usable area, depending on the size of the brush, becomes misaligned and unusable.

[nukeandbeans]

Additionally, adding these prefabs to the scene breaks their mesh and throws the same error as #222