Add implementation of forEachTransition to MDPSparse.

This accesses the MDP storage directly, rather than via getTransitionsIterator.
Not really used at the moment since methods that need to be fast, like matrix-vector
multiplication, are directly implemented already.

prism/src/explicit/MDPSparse.java

@@ -586,6 +586,14 @@ public class MDPSparse extends MDPExplicit
 		return choiceStarts[rowStarts[s] + i + 1] - choiceStarts[rowStarts[s] + i];
 	}
 
+	@Override
+	public void forEachTransition(int s, int i, TransitionConsumer c)
+	{
+		for (int col = choiceStarts[rowStarts[s] + i], stop = choiceStarts[rowStarts[s] + i + 1]; col < stop; col++) {
+			c.accept(s, cols[col], nonZeros[col]);
+		}
+	}
+
 	@Override
 	public Iterator<Entry<Integer, Double>> getTransitionsIterator(final int s, final int i)
 	{