StructOpts and Perturbation can now be combined, parsed src densities may be used with a different CommonWannier value (ChangeWannierCentres() is now externally callable)
StructOpt 1 with MaxOuterStep something and DoPerturbation 1 will now perform a structure optimization and subsequently the perturbation on the optimized structure. For this to work we needed a new enumerator ParseSrcDensities, which discerns between reading only occupied and all src densities. Thus, after the optimization is done, we read the written src densities and then immediately step on to to the perturbation minimisation.
This also allows for later perturbation with different CommonWannier values without re-minimisaition of occupied src densities.
