Documented sdl_iteration

src/main.cpp

@@ -128,12 +128,15 @@ int main(int argc, char** argv)
     bool sdl_mouse_l = false;
     bool sdl_mouse_r = false;
 
+    // The sdl_iteration counter is incremented every frame. It should never
+    // be used for timing purposes, use SDL_GetTicks for that.
+
+    unsigned long long sdl_iteration = 0;
+
     // Enter the main loop.
 
     bool sdl_running = true;
 
-    unsigned long long sdl_iteration = 0;
-
     while (sdl_running)
     {
     	// Remember the time at the start of the frame. At the end of the