Called when a message is printed to the chat box. Note, that this isn't working with player messages even though there are arguments for it.
1 number index
The index of the player.
2 string name
The name of the player.
3 string text
The text that is being sent.
4 string type
Chat filter type. Possible values are:
joinleave- Player join and leave messages
namechange- Player name change messages
servermsg- Server messages such as convar changes
teamchange- Team changes?
chat- (Obsolete?) Player chat?
none- A fallback value
Return true to suppress the chat message.