Continue work on custom blocks

[NicoNekoDev]

This continues the support for custom blocks.
Custom blocks can be defined as:

• Single names
  stone, grass_block, etc
• Provider names

1. ItemsAdder (itemsadder:<namespace>__<key>)
   Example: itemsadder:namespace__custom_block
2. Oraxen (oraxen:<id>)
   Example: oraxen:custom_block
3. Nexo (nexo:<id>)
   Example: nexo:custom_block
4. CraftEngine (craftengine:<namespace>__<key>)
   Example: craftengine:namespace__custom_block

[NicoNekoDev]

This is done.
Auxilor/libreforge#226