Variants-CIT

• custom_data module now has a caseSensitive option.

Changes to the Java API (non-breaking):

• Parameterized modules no longer need to register a constructor. They may be built directly from their codec instead.
• Special modules no longer need to register a constructor. They may be registered the same way as Simple modules.
• Special modules are no longer required to implement their variant logic separately from the special logic.
• The old ways of registering special and parameterized modules has been marked as deprecated.