Add bidirectional simplify method

[extremeheat]

It would be nice to have a simplify method that returns classes/objects that can be accessed like the current simplify method, but also allow for the data to be written back. We can set the object primitive valueOf() to match the nbt value like done in Protodef for BigInts

[extremeheat]

Actually, valueOf won’t be necessary. Just extending Array of Number I think is good enough + some instance of checks when writing to nbt

[rom1504]

yeah good idea
and we could have the same thing for https://github.com/PrismarineJS/node-mojangson (which is now using the same format as pnbt)