Fix handling of skinned meshes for nodes

- Rigidly animated models (e.g. the gltf frog node) were not working correctly,
  since cloning the mesh ignored the transformation matrices.
  Note that scaling the mesh needs to occur *after* transforming the vertices.
- Visual scale did not apply to skinned models,
  as resetting the animation overwrote scaled vertex data with static positions & normals.
  For backwards compatibility, we only apply a 10x scale to static (.obj) models.

src/client/mesh.h

@@ -93,10 +93,8 @@ void rotateMeshYZby (scene::IMesh *mesh, f64 degrees);
  */
 scene::IMeshBuffer* cloneMeshBuffer(scene::IMeshBuffer *mesh_buffer);
 
-/*
-	Clone the mesh.
-*/
-scene::SMesh* cloneMesh(scene::IMesh *src_mesh);
+/// Clone a mesh. For an animated mesh, this will clone the static pose.
+scene::SMesh* cloneStaticMesh(scene::IMesh *src_mesh);
 
 /*
 	Convert nodeboxes to mesh. Each tile goes into a different buffer.