Allows multi-precision work and paves the way for alternate BC's and such like
allowing for example G-parity which is important for K pipi programme.
In particular, can drive an extra flavour index into the fermion fields
using template types.
exp(-DeltaH) = 1 now, and plaquette is sensible. Will reproduce an old Wilson Gauge
Wilson Fermion SCRI plaquette with precision in mass matching shortly.
