Wrote a test that showed a Z field forces the state down.
Wrote a test that increasing the bandwidth leaves expectations unchanged.
Cosmetic:  Deleted unpaired fold marker
Switched convergence algorithms to use the new getConvergenceEnergy() method.
Now the convergence energy is correct for the infinite chain,
Now the infinite chain returns the correct convergence energy.
Wrote a (failing) test that simulates the infinite TI model.