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.
6000 matmuls CG unprec
2000 matmuls CG prec (4000 eo muls)
1050 matmuls PGCR on 16^3 x 32 x 8 m=.01
Substantial effort on timing and logging infrastructure
