Returns if the client has committed a team kill in the current round.
If this is set to 1 the client will be punished at the start of the
next round depending on the value of the mp_tkpunish cvar. The team
kill status is then reset.
1 if the client has committed a team kill, 0 otherwise
If the client index is not within the range of 1 to
MaxClients, or the client is not connected, an error will be