Bugfix: The photon was not integrated out from the top self-energy,
because the photon (VP) was set to 0 in the loop functions.  Therefore,
we have to look at the couplings, instead of the loop functions!
Add two simplification rules to avoid Power(x,-2) and Power(x,-0.5)
Add helper functions that sum all vector and matrix elements
Use rotated (mass) eigenstates in the calculation of the 1-loop
DRbar SM fermion masses, because we don't want to do a full
1-loop mass matrix diagonalization (there the external fields
should be in gauge eigenstates).
Add user helper function which avoids explicite setting of the
EWSB loop level
Use stricter fixed-size arrays as parameter to help the optimizer.
make iteration functions private to simplify the user interface
Since we no public setter for the EWSB loop order anymore, there
is no need to restore it after the run.
Do not expose the (internal) EWSB loop order to the user.