Added the following flags :
-c to make a NUMBER of pings
-f to add flood mode
-i to set an interval of NUMBER seconds between pings
-l to send a NUMBER of pings as fast as possible then swapping to normal mode
-q to add quiet mode
Refactored main.c :
Made flags.c for avoiding the main() function becoming a masterclass and make the file more readable
Moved some function from main.c to utils.c
Made some change to mimic the behavior of the ping binary of inetutils2.0
