Regression detection against case breakage

[gluap]

In #52 @codingcatgirl suggested to add a regression detection to the build:

By calculating the intersection of the PCB with the case one could validate that no accidental overlap happens.

Openscad can raise an error when it sees an empty geometry as a result of an intersection, which we could use as an indicator that everything is alright. However it was also mentioned that this is not 100% reliable with complex geometries