Mission Event: HandleChatMessageSent
Description: Fires when a message is sent by local player, before being broadcast to others. Return true to block a message from being broadcast to other clients/server, message would still be added to the senders chatlog unless blocked by HandleChatMessage.
Parameters:

• text: String - the chat message
• channel: Number - radio channel index
• isServerCommand: Boolean - Whether the command is a Server Command
• index: Number - Event handler handle