better model for 3d bookshelf

more efficient use of texture space, fewer polys, less wasted vertices.

also made it and empty bookshelf use default wood where possible, and
composite the inside-back texture from overlay + default wood.

homedecor_3d_extras/init.lua

@@ -1,21 +1,26 @@
 minetest.override_item("default:bookshelf", {
 	drawtype = "mesh",
 	mesh = "3dbookshelf.obj",
-	tiles = { "3dbookshelf.png"	},
+	tiles = {
+		"default_wood.png",
+		"default_wood.png^3dbookshelf_inside_back.png",
+		"3dbookshelf_books.png",
+	},
 	paramtype = "light",
 	paramtype2 = "facedir",
 })
 
+
 if minetest.get_modpath("moreblocks") then
 	minetest.override_item("moreblocks:empty_bookshelf", {
 		drawtype = "nodebox",
 		tiles = {
-			"3dbookshelf_top.png",
+			"default_wood.png^[transformR180",
-			"3dbookshelf_bottom.png",
+			"default_wood.png",
-			"3dbookshelf_sides.png",
+			"default_wood.png^[transformR90",
-			"3dbookshelf_sides.png",
+			"default_wood.png^[transformR270",
-			"3dbookshelf_fb_empty.png",
+			"default_wood.png^3dbookshelf_inside_back.png",
-			"3dbookshelf_fb_empty.png"
+			"default_wood.png^3dbookshelf_inside_back.png"
 		},
 		paramtype = "light",
 		paramtype2 = "facedir",