better packets

cmd/cgat/main.go

lib/backend/backends/v0/server.go

lib/frontend/frontends/v0/client.go

lib/perror/wrap.go

lib/pnet/errors.go

lib/pnet/packet/in.go

lib/pnet/packet/out.go

lib/pnet/packet/packets/v3.0/authenticationcleartext.go

lib/pnet/packet/packets/v3.0/authenticationmd5.go

lib/pnet/packet/packets/v3.0/authenticationok.go

lib/pnet/packet/packets/v3.0/authenticationresponse.go

lib/pnet/packet/packets/v3.0/authenticationsasl.go

lib/pnet/packet/packets/v3.0/authenticationsaslcontinue.go

lib/pnet/packet/packets/v3.0/authenticationsaslfinal.go

lib/pnet/packet/packets/v3.0/backendkeydata.go

lib/pnet/packet/packets/v3.0/errorresponse.go

lib/pnet/packet/packets/v3.0/negotiateprotocolversion.go

lib/pnet/packet/packets/v3.0/parameterstatus.go

lib/pnet/packet/packets/v3.0/passwordmessage.go

lib/pnet/packet/packets/v3.0/readyforquery.go