Added Network singleton
Added PacketType enum
Added NetworkPacket class
Added functions to the Network interface
Added INetworkListener interface
Moved INetworkListener to correct folder
Added INetworkListener to the project
Network: You can now add listeners
Added SFML system and network library
added SFML libraries
Added SFML packets to our NetworkPacket
Made some function parameters const
Merge branch 'NetworkInterface' into Developer