Improved Broadcast networking

BroadcastClient:
-BroadcastResponse now holds the base string received
-repeated values moved to constants
-error handling improved
+handles planned errors, else ends where appropriate, closing the socket

BroadcastServer:
-repeated values moved to constants
-now sends the lobbyInfo commandString as a response
-error handling improved
+handles planned errors, retries where possible, else ends where
appropriate, closing the socket
Merge branch 'master' of https://github.com/SEPRGroup/SEPR4Project