This regression was introduced in b3c058a9.

As of this commit, p2p will disconnect nodes directly after the
encryption handshake if too many peer connections are active.
Errors in the protocol handshake packet are now handled more politely
by sending a disconnect packet before closing the connection.

There were multiple synchronization issues in the disconnect handling,
all caused by the odd special-casing of Peer.readLoop errors. Remove the
special handling of read errors and make readLoop part of the Peer
WaitGroup.

Thanks to @Gustav-Simonsson for pointing at arrows in a diagram
and playing rubber-duck.

Message encoding functions have been renamed to catch any uses.
The switch to the new encoder can cause subtle incompatibilities.
If there are any users outside of our tree, they will at least be
alerted that there was a change.

NewMsg no longer exists. The replacements for EncodeMsg are called
Send and SendItems.

They got lost in the transition to rlpxFrameRW.

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.

The diff is a bit bigger than expected because the protocol handshake
logic has moved out of Peer. This is necessary because the protocol
handshake will have custom framing in the final protocol.

* ECIES moved from obscuren to ethereum
* Added html META[name=badge] to reflect menuItem.secondaryTitle

Overview of changes:

- ClientIdentity has been removed, use discover.NodeID
- Server now requires a private key to be set (instead of public key)
- Server performs the encryption handshake before launching Peer
- Dial logic takes peers from discover table
- Encryption handshake code has been cleaned up a bit
- baseProtocol is gone because we don't exchange peers anymore
- Some parts of baseProtocol have moved into Peer instead

- add const length params for handshake messages
- add length check to fail early
- add debug logs to help interop testing (!ABSOLUTELY SHOULD BE DELETED LATER)
- wrap connection read/writes in error check
- add cryptoReady channel in peer to signal when secure session setup is finished
- wait for cryptoReady or timeout in TestPeersHandshake

chop first byte when cryptoid.PubKeyS is set from identity.Pubkey() since this is directly copied in the auth message

- set proper public key serialisation length in pubLen = 64
- reset all sizes and offsets
- rename from DER to S (we are not using DER encoding)
- add remoteInitRandomPubKey as return value to respondToHandshake
- add ImportPublicKey with error return to read both EC golang.elliptic style 65 byte encoding and 64 byte one
- add ExportPublicKey falling back to go-ethereum/crypto.FromECDSAPub() chopping off the first byte
- add Import - Export tests
- all tests pass

- abstract the entire handshake logic in cryptoId.Run() taking session-relevant parameters
- changes in peer to accomodate how the encryption layer would be switched on
- modify arguments of handshake components
- fixed test getting the wrong pubkey but it till crashes on DH in newSession()

- add session token check and fallback to shared secret in responder call too
- use explicit length for the types of new messages
- fix typo resp[resLen-1] = tokenFlag

- correct sizes for the blocks : sec signature 65, ecies sklen 16, keylength 32
- added allocation to Xor (should be optimized later)
- no pubkey reader needed, just do with copy
- restructuring now into INITIATE, RESPOND, COMPLETE -> newSession initialises the encryption/authentication layer
- crypto identity can be part of client identity, some initialisation when server created