1.add standard server connection lesson
#fixme
this program needs to be tested with internet access, to figure out why it did not convert port number and ip address to network-order!
1.change "standard server" to CONNECT_TO_SERVER
2.add multiple clients server model
#fixme
the  CONNECT_TO_SERVER needs to be tested with internet access, to figure out why it did not convert port number and ip address to network-order!
1.fix lesson selecting logic
#fixme
the  CONNECT_TO_SERVER needs to be tested with internet access, to figure out why it did not convert port number and ip address to network-order!
1.improve lesson selecting logic...
#fixme
the  CONNECT_TO_SERVER needs to be tested with internet access, to figure out why it did not convert port number and ip address to network-order!