Returns the number of players currently in the game.
As players may join and leave a game at runtime, there can be "gaps" in player indexing, meaning player numbers may skip certain
values. GetPlayerCount returns the actual number of players, not the index of the last player plus one. To process all joined
players you need special handling (see example) - you cannot simply run from index 0 to GetPlayerCount() - 1. See the example
for
GetPlayerByIndex.
