Simple dithered motion blur effect, applied to whole rendering.

diff --git a/game.h b/game.h
index 1ad5131..d886e0b 100644
--- a/game.h
+++ b/game.h
@@ -347,6 +347,8 @@ struct
   char popupStr[LCR_POPUP_STR_SIZE];
   uint8_t popupCountdown;
 
+  int_fast8_t frameCycle;
+
   struct
   {
     uint8_t selectedTab;
@@ -399,6 +401,9 @@ uint8_t LCR_gameMusicOn(void)
 
 void LCR_gameDrawPixel(unsigned long index, uint16_t color)
 {
+  if ((index % LCR_SETTING_MOTION_BLUR_FRAMES) != LCR_game.frameCycle)
+    return;
+
 #if LCR_SETTING_RESOLUTION_SUBDIVIDE <= 1
   LCR_drawPixel(index,color);
 #else
@@ -1899,6 +1904,8 @@ uint8_t LCR_gameStep(uint32_t time)
     {
       LCR_LOG2("rendering next frame");
 
+      LCR_game.frameCycle = LCR_renderer.frame % LCR_SETTING_MOTION_BLUR_FRAMES;
+
       while (time >= LCR_game.nextRenderFrameTime)
         LCR_game.nextRenderFrameTime += 1000 / LCR_SETTING_FPS;
 
diff --git a/settings.h b/settings.h
index 332df45..4c28e70 100644
--- a/settings.h
+++ b/settings.h
@@ -222,6 +222,12 @@
   #define LCR_SETTING_TIME_MULTIPLIER 100
 #endif
 
+#ifndef LCR_SETTING_MOTION_BLUR_FRAMES
+  #define LCR_SETTING_MOTION_BLUR_FRAMES 2
+  /** Length of the motion blur rendering cycle. The longer, the more pronounced
+  the effect. Should be kept a power of two else performance suffers greatly. */
+#endif
+
 #ifndef LCR_SETTING_GHOST_STEP
   /** Step (in physics engine ticks) by which the samples for ghost car will be
   spaced (positions inbetween will be interpolated). Lower step along with more