Added api_endpoint API call to give local API endpoint address, added responses to local-only UDP API, added Socket::getSocketName(), added ability to discover current listening interface address and port for serveSocket-style functions

lib/socket.h

@@ -44,6 +44,7 @@ namespace Socket{
   bool checkTrueSocket(int sock);
   std::string resolveHostToBestExternalAddrGuess(const std::string &host, int family = AF_UNSPEC,
                                                  const std::string &hint = "");
+  bool getSocketName(int fd, std::string & host, uint32_t & port);
 
   /// A buffer made out of std::string objects that can be efficiently read from and written to.
   class Buffer{