Disable global/system chat, change gametype: COOP

The "Wasteland" Gametype was never official, and with the next update it
will give 'unkown gametype' errors in the loadscreen. So it was reverted
back to COOP.
The global chat served no real purpose and was only used for
trashtalking :)
JoinUnnassigned=0 will assign new players to the team with the least
players (they do still have the option to switch before clicking OK)