Add an interface description to EthernetTap, mostly for Windows.

node/EthernetTap.cpp

@@ -148,6 +148,7 @@ EthernetTap::EthernetTap(
 	const RuntimeEnvironment *renv,
 	const MAC &mac,
 	unsigned int mtu,
+	const char *desc,
 	void (*handler)(void *,const MAC &,const MAC &,unsigned int,const Buffer<4096> &),
 	void *arg)
 	throw(std::runtime_error) :
@@ -248,6 +249,7 @@ EthernetTap::EthernetTap(
 	const RuntimeEnvironment *renv,
 	const MAC &mac,
 	unsigned int mtu,
+	const char *desc,
 	void (*handler)(void *,const MAC &,const MAC &,unsigned int,const Buffer<4096> &),
 	void *arg)
 	throw(std::runtime_error) :

node/EthernetTap.hpp

@@ -62,6 +62,7 @@ public:
 	 * @param renv Runtime environment
 	 * @param mac MAC address of device
 	 * @param mtu MTU of device
+	 * @param desc If non-NULL, a description (not used on all OSes)
 	 * @param handler Handler function to be called when data is received from the tap
 	 * @param arg First argument to handler function
 	 * @throws std::runtime_error Unable to allocate device
@@ -70,6 +71,7 @@ public:
 		const RuntimeEnvironment *renv,
 		const MAC &mac,
 		unsigned int mtu,
+		const char *desc,
 		void (*handler)(void *,const MAC &,const MAC &,unsigned int,const Buffer<4096> &),
 		void *arg)
 		throw(std::runtime_error);

node/Network.cpp

@@ -150,7 +150,7 @@ SharedPtr<Network> Network::newInstance(const RuntimeEnvironment *renv,uint64_t
 	nw->_rlLimit.bytesPerSecond = ZT_MULTICAST_DEFAULT_BYTES_PER_SECOND;
 	nw->_rlLimit.maxBalance = ZT_MULTICAST_DEFAULT_RATE_MAX_BALANCE;
 	nw->_rlLimit.minBalance = ZT_MULTICAST_DEFAULT_RATE_MIN_BALANCE;
-	nw->_tap = new EthernetTap(renv,renv->identity.address().toMAC(),ZT_IF_MTU,&_CBhandleTapData,nw.ptr());
+	nw->_tap = new EthernetTap(renv,renv->identity.address().toMAC(),ZT_IF_MTU,(const char *)0,&_CBhandleTapData,nw.ptr());
 	nw->_id = id;
 	nw->_lastConfigUpdate = 0;
 	nw->_destroyOnDelete = false;