Formula engine: When possible, use synced RNG for the dice roll operator

src/formula.cpp

@@ -19,6 +19,7 @@
 #include "formula_callable.hpp"
 #include "formula_function.hpp"
 #include "map_utils.hpp"
+#include "random_new.hpp"
 
 #include <boost/foreach.hpp>
 
@@ -409,8 +410,11 @@ class operator_expression : public formula_expression {
 	static int dice_roll(int num_rolls, int faces) {
 		int res = 0;
 		while(faces > 0 && num_rolls-- > 0) {
-			// TODO: should we use the synced rng here ?
-			res += (rand()%faces)+1;
+			if(random_new::generator) {
+				res += (random_new::generator->next_random() % faces) + 1;
+			} else {
+				res += (rand() % faces) + 1;
+			}
 		}
 		return res;
 	}