pull in very simple client/server demo code

inspired by http://www.linuxhowtos.org/C_C++/socket.htm

source/client/net.h

@@ -1,4 +1,13 @@
 #ifndef _TTRTS_NET_H_
 #define _TTRTS_NET_H_
 
+#include <stdio.h>
+#include <stdlib.h>
+
+inline void error(const char *msg)
+{
+    perror(msg);
+    exit(1);
+}
+
 #endif