codecs update

codec/packet/login/client/packet.go

@@ -0,0 +1,19 @@
+package client
+
+import (
+	"github.com/Tnze/go-mc/data/packetid"
+	pk "github.com/Tnze/go-mc/net/packet"
+)
+
+type ClientboundPacket interface {
+	pk.Field
+	PacketID() packetid.ClientboundPacketID
+}
+
+type packetCreator func() ClientboundPacket
+
+var packetRegistry = make(map[packetid.ClientboundPacketID]packetCreator)
+
+func registerPacket(id packetid.ClientboundPacketID, creator packetCreator) {
+	packetRegistry[id] = creator
+}