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/roadveh_cmd.cpp

@@ -35,6 +35,7 @@
 #include "core/backup_type.hpp"
 #include "newgrf.h"
 #include "zoom_func.h"
+#include "framerate_type.h"
 
 #include "table/strings.h"
 
@@ -1587,6 +1588,8 @@ Money RoadVehicle::GetRunningCost() const
 
 bool RoadVehicle::Tick()
 {
+	PerformanceAccumulator framerate(PFE_GL_ROADVEHS);
+
 	this->tick_counter++;
 
 	if (this->IsFrontEngine()) {