big rendering overhaul (cleaning and api abstraction)

src/rendering/twn_rects.c

@@ -70,8 +70,6 @@ void render_rect_batch(const Primitive2D primitives[],
     /* single vertex array is used for every batch with NULL glBufferData() trick at the end */
     VertexBuffer const vertex_array = get_scratch_vertex_array();
 
-    use_texture_mode(batch.mode);
-
     /* vertex population over a vertex buffer builder interface */
     {
         VertexBufferBuilder payload = build_vertex_buffer(vertex_array, get_quad_payload_size(batch) * batch.size);