Fixed select new injuryToAdd always selects first

It should not always take the first injury in the list. That would with the current configuration almost always be the same injury as in `highestSpot`.

This might need to be expanded with something that prefers higher damage types.

extensions/medical/handleDamage.cpp

@@ -96,7 +96,8 @@ namespace ace {
                                 }
                                 else 
                                 { 
-                                    injuryToAdd = information.at(0); 
+                                    int indexNewInjuryToAdd = rand() % information.size();
+                                    injuryToAdd = information.at(indexNewInjuryToAdd); 
                                 }
 
                                 int bodyPartID = selection;