remove NodeARP in favor of arp.Handler; fix bug in IP stack node handling; use registerNode where applicable

examples/bridge/main.go

@@ -224,7 +224,7 @@ func run() (err error) {
 type Stack struct {
 	link    internet.StackEthernet
 	ip      internet.StackIP
-	arp     internet.NodeARP
+	arp     arp.Handler
 	udps    internet.StackPorts
 	dhcp    dhcpv4.Client
 	dns     dns.Client
@@ -427,7 +427,7 @@ func (s *Stack) ResultResolveHardwareAddress6(ip netip.Addr) (hw [6]byte, err er
 	if err != nil {
 		return hw, err
 	} else if len(hwslice) != 6 {
-		panic("unreachable slice hw leng")
+		panic("unreachable slice hw length")
 	}
 	return [6]byte(hwslice), nil
 }

examples/stack/main.go

@@ -181,7 +181,7 @@ type Stack struct {
 	ethernet internet.StackEthernet
 	ip       internet.StackIP
 	tcpports internet.StackPorts
-	arp      internet.NodeARP
+	arp      arp.Handler
 }
 
 func (stack *Stack) Reset(ourMAC, gwMAC [6]byte, ip netip.Addr, mtu int) (err error) {

examples/stackbasic/main.go

@@ -195,7 +195,7 @@ func NewEthernetTCPStack(ourMAC, gwMAC [6]byte, ip netip.AddrPort, mtu uint16, s
 	if err != nil {
 		return nil, nil, err
 	}
-	err = ipStack.RegisterTCPConn(&conn)
+	err = ipStack.Register(&conn)
 	if err != nil {
 		return nil, nil, err
 	}