modify README.md
include standard header files
define options struct
declare global variables
add function to initialize options to deafult values
parse command line args
write help stub
change address struct to sockaddr
do some error checking
write bye function

prints error message to stderr and exits program
replace error messages with bye
don't accept invalid ports on command line
parse target ip address and port number in case of client mode
write die function
write basic socket wrapper functions
solve bug in parsing port number in client mode
add Inet_pton wrapper function
provides common functionality for client mode and lsiten mode
write Select, Read and Write wrapper functions
remove global sockfd and socket addr struct variables