1.this tool illustrate how one can use SOCK_STREAM
to transfer file through AF_INET(IPv4)
2. nonblock io is introduced


TODO: 
1.  one can use f.seek + f.tell to get the filesize, and calc the process 

known bugs : 


files more than 337M would have problem (usually broke at 337M or 338M or so, might be timeout? ) 
reason is still unkonwn 


usage:  no compile is needed but python is required
	python pycpd.py  # as server 
	python pycp.py  <host> <host_filelocation> <dest_filelocation>  # as client command line