Added TCP echo server and modified example to use it

examples/tcp_client/README.md

@@ -1,2 +1,4 @@
 # TCP client example
 This example shows how to create a TCP client and send and receive TCP data.
+
+There's a Python based echo server in the tools folder. Start it by running `python echoserver.py` from a terminal. Connect to it from `localhost:5555`.

examples/tcp_client/tcp_client.gui_script

@@ -1,6 +1,6 @@
 local tcp_client = require "defnet.tcp_client"
 
-local SERVER_PORT = 5000
+local SERVER_PORT = 5555
 
 function init(self)
 	msg.post(".", "acquire_input_focus")
@@ -43,6 +43,6 @@ function on_input(self, action_id, action)
 				gui.set_enabled(self.send, false)
 			end)
 	elseif gui.pick_node(self.send, action.x, action.y) and gui.is_enabled(self.send) then
-		self.client.send("foobar " .. tostring(os.time()))
+		self.client.send("foobar " .. tostring(os.time()) .. "\r\n")
 	end
 end

tools/echoserver.py

@@ -0,0 +1,39 @@
+# Example of simple echo server
+# www.solusipse.net
+# https://gist.github.com/solusipse/6419144
+
+import socket
+
+
+def listen():
+    connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    connection.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    connection.bind(('0.0.0.0', 5555))
+    connection.listen(10)
+    print "Waiting for connection"
+    while True:
+        current_connection, address = connection.accept()
+        print "Client connection " + str(address)
+        while True:
+            data = current_connection.recv(2048)
+
+            if data == 'quit\r\n':
+                current_connection.shutdown(1)
+                current_connection.close()
+                break
+
+            elif data == 'stop\r\n':
+                current_connection.shutdown(1)
+                current_connection.close()
+                exit()
+
+            elif data:
+                current_connection.send(data)
+                print data
+
+
+if __name__ == "__main__":
+    try:
+        listen()
+    except KeyboardInterrupt:
+        pass