BUG: Edge refinement of directed electrodes

[j-zimmermann]

In the directed electrodes, some edges are not marked for local refinement.
That means, the edge size cannot be set.
I started rewriting the code in 7733612.
Please have a look and add fixes here. Only the directed electrodes should be affected.

[j-zimmermann]

I figured out that at least for the Boston Scientific Vercise not all edges of the directed contact had been labelled.
See more at b90db58. I added a test script that writes ParaView files and can be used to check if the refinement works.