Fix: the alive cache is updated in the addDead methods.

Calling this method is no longer needed after removing a player.
Fix: when unfreezing the whole game, only the previously-running timers are resumed.
Fix: empty teams are not taken into account by the spawns generator and the initial teleportation.
Improved the help messages for /uh spawns generate.
Feature: you can display the state of the game in the MOTD.
Fix: the players were teleported to the spawn during the slow start in case of relog.