Support for IPLD Data Model and Codecs

[tysonzero]

I was looking to manipulate and serialize/deserialize IPLD objects, and I came across a few of the libraries listed here in the process.

It looks like the current set of libraries does not include the above, so I figured I'd make an issue in case you thought it was in scope.

I may end up making the libraries myself in my free time, likely on top of some of your libraries, in which case I'll open source them and we can discuss if it's worth merging them into your repo later.