Added a benchmark tool

Source/Problem21.cpp

@@ -34,6 +34,10 @@
 int Problem21::LIMIT = 10000;	//The top number that will be evaluated
 
 Problem21::Problem21() : Problem("Evaluate the sum of all the amicable numbers under 10000"){
+	reserveVectors();
+}
+
+void Problem21::reserveVectors(){
 	divisorSum.reserve(LIMIT);	//Reserving it now makes it faster later
 	divisorSum.resize(LIMIT);	//Make sure there are enough spaces
 }
@@ -113,3 +117,10 @@ uint64_t Problem21::getSum() const{
 	}
 	return mee::getSum(amicable);
 }
+
+void Problem21::reset(){
+	Problem::reset();
+	divisorSum.clear();
+	amicable.clear();
+	reserveVectors();
+}