Added common codebase as a subproject.
Renamed prefix.h and added Packet.h which describes different packet types.
Added new includes to CMakeLists.txt and added SOFT336_VOIP_PROTO_FILE variable.
Updated .gitignore
Removed CMakeLists.txt.user file.
Began working on user connection.
Added reference to the user object inside VoipClient and ConnectWidget.
Setup initial UserList.cpp file.