Several changes, add placeholder classes, img, etc

Several changes:

./_builder/buffer.php -> if folder doesnt exists, create it; The folder was not being generated, even with the item class existing, so we need to create the folder before anything

./rebuild.php -> add password to rebuild, add message, add read password from config
./config.php -> password setting

./_builder/rendering/root.php -> add under construction item/resource/mechanic href

./_builder/rebuildAll.php -> add item, resources, mechanics

Add missing texture block and image to show that is still missing

Resources, Items, Mechanics:
Object renderization (WIP), shamelessy copied from block.php and replaced block with item,mechanic,resource;
Placeholder only, so the rebuild automagically creates the item folder, the file can be replaced entirely as it follows the pattern
./_builder/item.php
./_builder/resource.php
./_builder/mechanic.php
./_data/items.php
./_data/resources.php
./_data/mechanics.php