Added include guard

Stopwatch.hpp

@@ -4,6 +4,8 @@
 //Modified: 10-30-2018
 //This file creates a class that can be used on many programs to time them
 
+#ifndef STOPWATCH_HPP
+#define STOPWATCH_HPP
 
 #include <chrono>
 
@@ -78,3 +80,5 @@ public:
 		endTime = startTime = std::chrono::high_resolution_clock::time_point();
 	}
 };
+
+#endif //end STOPWATCH_HPP