Postcard

A (TODO), no_std, serde compatible message library for Rust.

Design plans

1. usizes are [varint]s
2. enum variants are usizes
3. variable length data, like strings and vecs, are prefixed by their length as a [varint]/usize, e.g. "hello" is [5, h, e, l, l, o]
4. [heapless] data structures are used as the first class serialization/deserialization target.
5. there will be a std feature that allows you to either auto-convert from heapless to non-heapless, or jump directly to that, whatever is easier