Update proto spec

[ethanfrey]

This addresses concerns raised by @cwgoes here: cosmos/ibc#282 (comment)

Notably, the spec now fixes the hash algorithm for inner nodes and optionally allows setting a min and max depth for the trees (min/max number of inner nodes).

[cwgoes]

ACK, although do you want to add tests for the spec mis-matching (hash / min depth / max depth)?

I believe that this addresses all the specifically ICS23-related concerns in cosmos/ibc#282 (comment); we still need to check the CommitStore and sub-store logic though (in any case).

[ethanfrey]

Thank you for the review

ACK, although do you want to add tests for the spec mis-matching (hash / min depth / max depth)?

There is a test for hash. I will add some for min/max depth. As well as the Rust and JS implementations.

I believe that this addresses all the specifically ICS23-related concerns in cosmos/ibc#282 (comment); we still need to check the CommitStore and sub-store logic though (in any case).

This is changes in the SDK. I can help with those as well, but that is not in this repo. I would demo how to use ics23/tendermint to make proofs for the CommitStore (but we need to change it to use merkle proofs, not just amino-serialize the roots of all sub-stores and hash it)

[ethanfrey]

@cwgoes I extended the tests for go to enforce min/max depth and made the same test cases for both TypeScript and Rust and updated validation logic in both.

I believe this is completed. Happy for one more review from you, and will merge and tag upon approval

[cwgoes]

utACK - thanks! Looking forward to using this in the SDK.