The state model of the NetClient and NetServer is intransparent at times and some names are confusing or contradictory.
This patch adds an exact specification to every state, so that it should be easier to keep track of the code flow.
Rename OnAuthenticate to OnAuthenticateResult in the NetClient because it processes the AuthenticateResult packet and
because it should not be confused with OnAuthenticate in the NetServer which processes the Authenticate packet.
Rename SERVER_STATE_PREGAME, NCS_PREGAME to SERVER_STATE_GAMESETUP, NCS_GAMESETUP.
This avoids confusion with NSS_PREGAME which contrary to the renamed ones includes the loading screen.
Rename NCS_INITIAL_GAMESETUP to NCS_AUTHENTICATED to avoid confusion with the gamesetup stage.
Add missing member initialization in the constructors.
Uses 0 as the second argument for enet_peer_timeout to be consistent with the other call.
(causative confirmed in irc yesterday fwiw)
(The second argument is unneeded since the minimum timeout is about infinity, see also http://enet.bespin.org/group__peer.html#gac48f35cdd39a89318a7b4fc19920b21b)