Update FEMMT for current waveform with DC-offset #76
Description
Actually FEMMT cannot simulate magnetic components, which get current with DC-offset. This leads to a shift of average of the magnetic field strength away from zero. This leads to an error within FEMMT.
The idea is to maps the shifted mean value of the magnetic field strength back to a current form without DC offset. This corresponds to a transformation of the applied current waveform calculation within FEMMT.