client-clear.py: bugs in main() and read_argument() fixed

read_argument(): return now outside from while loop. loop works now until a valid value ist
entered. main(): reads now a return value from server and close the socket.

client-clear.py

@@ -58,6 +58,12 @@ def main():
         except Exception as e:
             print('Error: {}'.format(e))
             exit()
+        try:
+            res = mySocket.recv(1)
+            print('Server returns: {}'.format(res.decode()))
+        finally:
+            mySocket.close()
+            print('Disconnect from server')
 
 
 if __name__ == '__main__':