Todo: update Cosmos SDK and Tendermint types

[jordaaash]

While resolving #7, I noted that some file names and types in go/lib are out of sync with the versions of the SDK and Tendermint in use.

It's possible that this library's copies were based on the master repositories of the SDK and Tendermint at the time rather than the fixed version releases. I'll be going over the SDK @ 0.35.0 and Tendermint @ 0.31.7 in the fix-types branch to update.

This is also relevant to the work that needs to be done on #3. Figuring out a solution to automate this process might be in scope.