Updated mcast.c to the latest version.  The logic needs to be completely redone in order to reflect the design document.  Circular queue data system is no longer needed, it can be managed in the main() process with a few ints and a static array.  packet.h has been updated to reflect the changes in the design document to improve identification of tokens. mcast_start has been properly renamed to start_mcast, as specified in the project description.