Bugfix: Rewrite setupCache()

Given an element, during the setup geometryInInside() and geometryInOutside() is called for each face where the latter is nonsense for boundary faces and that's why UGGrid started complaining. So remove all geometryInOutside() calls. It is not required anyway because this way of setting up the cache before using the operator is only for conforming grids.

Secondly rewrite the code in terms of range-based for.