Check whether static particle is below cylinder in PlanarSurfacePair formation
Some cleanup
Rename 'testMixedPair1DCap' into 'testMixedPair1DStatic' to generalize

We will use this domain both for the case in which a 1D particle on the rod
interacts with a static cap-bound particle and for the case in which it
interacts with a static plane-bound particle (CylindricalSurfacePlanarSurfaceTransferSingle).
Same renaming for the associated pair domain
One more important check
Convert assert statement to exception that can be handled
Generalize construction of MixedPair1DCap to MixedPair1DStatic, i.e.
also to the cases when the static particle is on the plane
All interactions need property self.product_structure
Not selfish enough...