preparing to pass integrator, smearing, bc's as policy classes to hmc.
Propose to unify "integrator" and integrator algorithm in a base/derived
way to override step. Want to read through ForceGradient to ensure
that abstraction covers the force gradient case.
to a little figure out what Guido had done & why -- but there is a neat saving of force
evaluations across the nesting time boundary making use of linearity of the leapP in dt.
I cleaned up the printing, reduced the volume of code, in the process sharing printing
between all integrators. Placed an assert that the total integration time for all integrators
must match at end of trajectory.
Have now verified e-dH = 1 for nested integrators in Wilson/Wilson runs with both
Omelyan and with Leapfrog so substantial confidence gained.
So valence sector looks ok.
FermionOperatorImpl.h provides the policy classes.
Expect HMC will introduce a smearing policy and a fermion representation change policy template
param. Will also probably need multi-precision work.
* HMC is running even-odd and non-checkerboarded (checked 4^4 wilson fermion/wilson gauge).
There appears to be a bug in the multi-level integrator -- <e-dH> passes with single level but
not with multi-level.
In any case there looks to be quite a bit to clean up.
This is the "const det" style implementation that is not appropriate yet for clover since
it assumes that Mee is indept of the gauge fields. Easily fixed in future.
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.
