Block data (similar to param2 in Minetest)

[Unarelith]

We have 16 bits for custom block data. Its 5 first bits are currently used for rotation when it's enabled, but it's possible to do more.

• The engine should allocate the bits dynamically depending on what's in the block definition, for example:

  • If you define 5 states (Block states #138), you only need 3 bits
  • If you define the block as rotatable, you will need 5 bits
  • etc...

• The block definition loading should fail if the engine needs to allocate more than 16 bits, and the error message should list what are the allocated bits used for.

• Also, a new block field custom_data_size = x could be added to allocate x bits of the data