Support new config method.

Refined code.

params_windows.go

@@ -1,3 +1,5 @@
+// +build windows
+
 package water
 
 // PlatformSpecificParams defines parameters in Config that are specific to
@@ -9,10 +11,22 @@ type PlatformSpecificParams struct {
 	// use the default ComponentId. The default ComponentId is set to tap0901,
 	// the one used by OpenVPN.
 	ComponentID string
+	// Network is required when creating a TUN interface. The library will call
+	// net.ParseCIDR() to parse this string into LocalIP, RemoteNetaddr,
+	// RemoteNetmask. The underlying driver will need those to generate ARP
+	// response to Windows kernel, to emulate an TUN interface.
+	// Please note that it cannot perceive the IP changes caused by DHCP, user
+	// configuration to the adapter and etc,. If IP changed, please reconfigure
+	// the adapter using syscall, just like openDev().
+	// For detail, please refer
+	// https://github.com/OpenVPN/tap-windows6/blob/master/src/device.c#L431
+	// and https://github.com/songgao/water/pull/13#issuecomment-270341777
+	Network string
 }
 
 func defaultPlatformSpecificParams() PlatformSpecificParams {
 	return PlatformSpecificParams{
-		ComponentId: "tap0901",
+		ComponentID: "tap0901",
+		Network:     "192.168.1.10/24",
 	}
 }