Vector fields require different boundary conditions

[jhbdiehl]

In Transformer: Eqs. 4.4 in Theoretical foundations dont hold for z component, bc. perpendicular to surface. Therefore instead of Ez(r) = Ez(r+1) need Dz(r) = Dz(r+1)!
Also needs to be done in recurprop. in some way.

Changes should be minimal, bc z component is very small. However, as it is it's just wrong!