Correctly format WinSock errors with a message

This has lead to many(!) issues in the past, and makes
life harder for everyone doing support. This will display the
error code, together with an error message windows provides.

include/Server.h

@@ -38,6 +38,7 @@ private:
     void UpdateUl(bool D, const std::string& msg);
     std::unique_ptr<sockaddr_in> UDPSockAddress;
     void ServerParser(const std::string& Data);
+    static std::string GetSocketApiError();
     void TCPSend(const std::string& Data);
     void UDPParser(std::string Packet);
     void SendLarge(std::string Data);