Add fill_rect function

src/window.c

@@ -81,3 +81,11 @@ void draw_rect(const window_t *wnd, const rect_t *rect, colour_t colour) {
 
   SDL_RenderDrawRect(wnd->renderer, &dst);
 }
+
+void fill_rect(const window_t *wnd, const rect_t *rect, colour_t colour) {
+  set_colour(wnd, colour);
+
+  SDL_Rect dst = {rect->topleft.x, rect->topleft.y, rect->w, rect->h};
+
+  SDL_RenderFillRect(wnd->renderer, &dst);
+}