Added ability to draw a non-filled rectangle

include/GameEngine.h

@@ -61,13 +61,14 @@ WindowSize get_window_real_size();
  */
 WindowDrawingArea get_window_drawing_area();
 
+void draw_rectangle(RenderRect rect, SDL_Color color);
 void fill_rectangle(RenderRect rect, SDL_Color color);
 
 /**
  * Ensures that a rendered rectangle is clipped to the drawing area when it is
  * smaller than the actual size of the window.
  */
-void clip_source_rect_to_drawing_area(RenderRect *src, RenderRect *dest);
+void clip_render_rects_to_drawing_area(RenderRect *src, RenderRect *dest);
 
 RenderRect get_texture_asset_rect(AssetID id);
 void render_texture_asset(AssetID id, RenderRect *src, RenderRect *dest);