The beta has been updated. The parsed keys (spawns, team size, deathmatch info) are now actually put to use, and an option has been added that allows disabling auto assign instead of putting players into the appropriate team. Thanks urban360 for the hint regarding keys.
Things that still need improving:
I should be using engclient_cmd instead of client_cmd.
Keys are evaluated each time a player joins. This should only be done once, e.g. by using a flag.
There are warnings because I'm using an "if" condition for the debug code. I could use a compiler directive instead, or a cvar to toggle debug mode.
Edit: Fixed in beta 4.