Add piston variant rendering & fix lighting

- Fix extended pistons rendering as if they were retracted
- Fix retracted pistons rendering completely dark when using a
  lighting rendermode primitive
- Use piston head 'facing' property to determine rotation
- Use piston head 'type' property to determine if sticky or not

overviewer_core/src/primitives/lighting.c

@@ -316,9 +316,10 @@ lighting_draw(void* data, RenderState* state, PyObject* src, PyObject* mask, PyO
         if ((state->block_pdata & 4) == 4) { /* bottom right */
             do_shading_with_mask(self, state, x, y, z + 1, self->facemasks[2]);
         }
-        /* leaves and ice are transparent for occlusion calculations but they 
-         * per face-shading to look as in game */
-    } else if (is_transparent(state->block) && (state->block != 18) && (state->block != 79)) {
+        /* leaves, ice, and pistons are transparent for occlusion calculations
+         * but they need per face-shading to look as in game */
+    } else if (is_transparent(state->block) &&
+               !block_class_is_subset(state->block, (mc_block_t[]){block_leaves, block_ice, block_piston, block_sticky_piston}, 4)) {
         /* transparent: do shading on whole block */
         do_shading_with_mask(self, state, x, y, z, mask_light);
     } else {