p2p: replace network id with genesis id

[dshulyak]

part of: spacemeshos/pm#135
depends on: #3505

• remove NetworkID from configuration
• initialize p2p.Host with genesis id (pass it to handshake.New)
• replace field in handshake message https://github.com/spacemeshos/go-spacemesh/blob/develop/p2p/handshake/handshake.go#L45 and relevant test

[WilfredTA]

Not sure if handshake field needs to be replaced here? Currently, just setting p2p NetworkId with a uint32(GenesisId)

go-spacemesh/config/config.go

Line 217 in 569a1ae

func (cfg *Config) NetworkIdFromGenesis(genCfg *GenesisConfig) {

[dshulyak]

Why not to use genesis id in the handshake and remove network id as was discussed in the Lane's spec?

[WilfredTA]

Its just naming difference at this point - genesis ID is used as the network id. I think this is compliant with Lane's spec

[dshulyak]

It reduces genesis id to 4 bytes and calls it network id. This is just some strangeness honestly, can we do a straightforward thing

[WilfredTA]

Yeah, we can do that. Thanks for the input