corrected some conceptual mistakes in StandardHamiltionian that had no effects...

corrected some conceptual mistakes in StandardHamiltionian that had no effects because the prior metric is 1

nifty5/operators/energy_operators.py

@@ -328,8 +328,8 @@ class StandardHamiltonian(EnergyOperator):
             return self._lh(x) + self._prior(x)
         else:
             lhx, prx = self._lh(x), self._prior(x)
-            mtr = SamplingEnabler(lhx.metric, prx.metric.inverse,
-                                  self._ic_samp, prx.metric.inverse)
+            mtr = SamplingEnabler(lhx.metric, prx.metric,
+                                  self._ic_samp)
             return (lhx + prx).add_metric(mtr)
 
     def __repr__(self):