StateValuesDV: Fix output when indices are not to be printed

A : was printed in front of the state variable values, even though
no index was printed, i.e.,

:(3,2,5)=0.5

Only print : after index, as is done for explicit printing. StateValuesMTBDD
currently does not support index-less printing.

prism/src/prism/StateValuesDV.java

@@ -629,10 +629,9 @@ public class StateValuesDV implements StateValues
 				}
 			} else {
 				if (printIndices) {
-					outputLog.print(n);
+					outputLog.print(n + ":");
 				}
 				if (printStates) {
-					outputLog.print(":");
 					outputLog.print("(");
 					j = varList.getNumVars();
 					for (i = 0; i < j; i++) {