Merge branch 'develop_pull_request' of https://github.com/tendermint/ethermint into tendermint-develop_pull_request

It is unused and untested right now. We can
bring it back later if required.

Until chunked frames are implemented we cannot send messages
with a size overflowing uint24.

They got lost in the transition to rlpxFrameRW.

With RLPx frames, the message code is contained in the
frame and is no longer part of the encoded data.

EncodeMsg, Msg.Decode have been updated to match.
Code that decodes RLP directly from Msg.Payload will need
to change.

This mostly changes how information is passed around.
Instead of using many function parameters and return values,
put the entire state in a struct and pass that.

This also adds back derivation of ecdhe-shared-secret. I deleted
it by accident in a previous refactoring.

JIT build fixes