GSA: Add warning if facets overlap

[hamogu]

Unless the distance between facets is very large, there is a series risk that they overlap on the corners, if one is not careful to rotate them around the circle.
A "collision detection" that warns in this case should be added.
"shapely" might be the correct package to do so.

[hamogu]

A sort of "collision detection" would be useful in general. I don't think this needs to be programmed in MARXS, rather the geometry needs to be exported to some other format (shapely?) for which a python package performing 3 d collision detection exists.