Tempering without Fermion weights
At the moment, the tempering code calculates the Fermion weight to determine the acceptance of an exchange and the Green function gets recalculated. But if the Fermion dynamics do not depend explicitly on the parameter that gets varied while tempering, which is for example the case if one varies the transverse field h of a Transverse Ising model. I've started on implementing a flag for the parameter-file to do tempering without Fermion weights which should speed up the tempering dramtically. I believe the only thing missing is a way to transmit UDV-States between MPI-processes.