ID should only exist in factories

[calclavia]

It doesn't make sense to have getID() in block, because you can have different instance of block, and have them considered as different types.

It makes more sense to have IDs in factories, because factories are what determines the type of block/entity/item, not the instance itself.

E.g: It doesn't make sense as we're registering instances of TE essentially as a specific type.

Before

blockManager.register(constructor);

ID used to be specified in block instances, which does not make sense.

After

New registration pattern for blocks, items and entities:

blockManager.register(id, constructor);

Example:

blockManager.register("stone", BlockStone::new);

TODO: #196

[codecov-io]

Current coverage is 12.81%

Merging #191 into master will increase coverage by +0.40% as of fcb82ed

@@            master    #191   diff @@
======================================
  Files          389     391     +2
  Stmts        10383   10411    +28
  Branches      1486    1488     +2
  Methods          0       0       
======================================
+ Hit           1289    1334    +45
  Partial         76      76       
+ Missed        9018    9001    -17

Review entire Coverage Diff as of fcb82ed

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[calclavia]

PR Complete. Tested and working.

@Kubuxu, @RX14, @Smesper @balthatrix