Ensure frozen ATs are still executed every block.

We currently want to execute frozen ATs, to maintain backwards support. We could optionally choose to stop executing them later, via a hard fork.

src/main/java/org/qortal/at/AT.java

@@ -131,6 +131,8 @@ public class AT {
 
 		// Nothing happened?
 		if (state.getSteps() == 0 && Arrays.equals(stateHash, latestAtStateData.getStateHash()))
+			// We currently want to execute frozen ATs, to maintain backwards support.
+			if (state.isFrozen() == false)
 				// this.atStateData will be null
 				return Collections.emptyList();