OpenMW-CS: Cell border lines don't update properly on terrain change
In OpenMW-CS, the green lines marking cell borders continue to get added to the drawing for every terrain change. They persist even when undoing terrain changes. ![cell_border_bug](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)
The expected behavior would be to always display a single green line that conforms to the current shape of the terrain.