Updater: Applied the DENG2_PIMPL macro in UpdaterSettingsDialog
libdeng2: Allow using de::Address in a QVariant
libdeng2: Beacon discovery needs a unique UDP port

Each Beacon doing discovery needs to have a UDP port of its own, or
it may not be the one that receives the replies.
Shell|GUI: Opening a connection

Added a dialog for specifying which server to connect to. Log entries
and other packets received from the server are handled in the context
of the connection window (rather than application-wide).