Update v2.1.0

• Partial test coverage
• Fix incorrect int[] decoding (#9)
• Clean-up NBTList and NBTCompound
  • Improved documentation
  • Change superclasses from ArrayList to AbstractList, and HashMap to AbstractMap respectively
• Clean-up TagType
  • Improved documentation
  • Deprecate getClazz() in favor of getRuntimeType(). Functionally, they are exactly the same.