ReDecay option to decay all heavy flavours

Redecay option that redecays the all particles with at least the signal's flavour. This is mainly intended to improve ReDecay performance for FT as with the "redecay everything heavier than the signal" option it is not guaranteed that the opposite side is redecayed as well (this is caused by the additional, implicit requirement that particles that are redecayed must have been decayed by EvtGen).

Unrelated: for future Gauss, this code will be restructured to reduce the code bloat.