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

Conflicts:
	cmd/utils/cmd.go

Conflicts:
	eth/block_pool.go
	eth/block_pool_test.go
	eth/protocol_test.go
	miner/worker.go

[WIP] Update Readme 

Updated JSON log events

Remove Websockets RPC transport

- best peer cannot be idle for more than idleBestPeerTimeout
- introduce ErrIdleTooLong fatal error
- modify default values

9e3fe72 update state root hash

git-subtree-dir: tests/files
git-subtree-split: 9e3fe720e3d46f046e06a91e45c881e79557f721