made new space harmonic iff initial space is harmonic

nifty5/operators/central_zero_padder.py

@@ -64,7 +64,7 @@ class CentralZeroPadder(LinearOperator):
             raise ValueError("New shape must be larger than old shape")
 
         # make target space
-        tgt = RGSpace(new_shape, dom.distances)
+        tgt = RGSpace(new_shape, dom.distances, harmonic=dom.harmonic)
         self._target = list(self._domain)
         self._target[self._space] = tgt
         self._target = DomainTuple.make(self._target)