Feature: Framerate display window (#6822)

Frame rate and various game loop/graphics timing measurements and graphs. Accessible via the Help menu, and can print some stats in the console via the fps command.

src/window.cpp

@@ -36,6 +36,7 @@
 #include "error.h"
 #include "game/game.hpp"
 #include "video/video_driver.hpp"
+#include "framerate_type.h"
 
 #include "safeguards.h"
 
@@ -3077,6 +3078,9 @@ void InputLoop()
  */
 void UpdateWindows()
 {
+	PerformanceMeasurer framerate(PFE_DRAWING);
+	PerformanceAccumulator::Reset(PFE_DRAWWORLD);
+
 	Window *w;
 
 	static int highlight_timer = 1;