add the long awaited push_9slice

include/twn_rendering.h

@@ -38,6 +38,8 @@ TWN_API void push_circle(Vec2 position, float radius, Color color);
 TWN_API void push_text(char *string, Vec2 position, int height_px, Color color, const char *font_path);
 TWN_API int text_get_width(char *string, int height_px, const char *font_path);
 
+TWN_API void push_9slice(char *texture_path, int texture_w, int texture_h, int border_thickness, Rect rect, Color color);
+
 /* pushes a textured 3d triangle onto the render queue */
 /* vertices are in absolute coordinates, relative to world origin */
 /* texture coordinates are in pixels */