IBC reference implementation tracking issue

[cwgoes]

Reference implementations for IBC won't be developed in this repository, but they will be referenced in various ICS standards documents, so I think it makes sense to track them here.

I think we should aim to have two separate, wire-compatible, reference implementations of "minimum viable useful IBC" as defined in #26, including fungible token transfer.

One implementation will be in the Cosmos SDK, in Golang. I think that one should be developed first.

The second implementation is TBD. Possibly, it could be in Javascript as part of Lotion, although I'm a bit skeptical of Javascript's suitability as a reference implementation language. Likely Javascript would be a better choice for prototyping and testing new application-layer additions to IBC. I think one candidate is Rust, which would facilitate usage in Substrate and possibly future SDK/Tendermint incarnations in Rust.

I think we should complete & test both implementations before launching IBC on the Hub.

[ebuchman]

Thanks Chris. I'd like to see the ICF tackle the Rust implementation here, and ideally Agoric+Nomic tackle the Javascript. I think having three in parallel will be super valuable, especially given the different niches that these languages occupy.

[cwgoes]

Tracking issue for the first MVP in the Cosmos SDK: #95

[cwgoes]

Closing in favor of #145 and ECOSYSTEM.md.

The latter should become the canonical list of implementations.