partial network integration into Multiplayer

TransferBar:
-added clearLeft(), clearRight() as utility functions

Multiplayer:
-made public so that other scenes outside the package can use it
-removed test logic
-integrated networking into transfer logic
-added MultiplayerPacket
+stores code and object to allow conditional typecasting of packet
contents
Merge branch 'master' of https://github.com/SEPRGroup/SEPR4Project