call: set up invitation link to join game, spectate, and begin/cancel.

all players get swPool_poolplay and swPool_spec, spectator only gets swPool_spec

game begin when you join and hit begin.
can't join if already two players chose the same room.
if another player register for your same game, you two can go.
    Now: remove everyone in the waiting room when one game starts, keep the 1/2 players and all spectators.

consider placing players in teams if display the score in sidebar.

swPool_mute does not see the tellraw in this section.