Rename IBC Height's "Version" to a unique name for IBC

[colin-axner]

Summary

There continues to be confusion around the IBC height which originally used "epoch" and now uses "version". Version collides with the IAVL tree usage of version. We propose renaming the name to something that can be more uniquely identifier with IBC to avoid naming collision and confusion

@cwgoes proposed possibly using:

• edition
• revision

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[cwgoes]

Let's choose "revision" here.

[ValarDragon]

I'm still in favor of prefixing LiteClient to whatever name is chosen, so that the variable / concept name is self-contained.

[colin-axner]

I'm still in favor of prefixing LiteClient to whatever name is chosen, so that the variable / concept name is self-contained.

I don't think that would help in this case since a revision number is actually referencing the revision of a chain not a light client. ie cosmos-hub-4 is the 4th revision.

From the implementation side, I think using Revision will be pretty well self-contained. It will be embedded in the height struct which is contained in x/ibc/core/02-client/types/height.go and only used in IBC. Furthermore the Height type is only used within the ClientState struct for light clients and as the key when referencing the ConsensusState of a light client

[colin-axner]

This should be tackled after we merge the upgrade consensus state change to avoid merge conflicts

[AdityaSripal]

Decided upon Revision