Channel should trigger a channelSend event on sender

[shawncplus]

Channel right now on send triggers a channelReceive event on targets of the message but does not trigger any analogous event on the sender of the message. As such it's not possible at the moment to script for a player saying something if there are no targets

[shawncplus]

In addition to this a new config option should be added to Channel: boolean eventOnly (false). If eventOnly is true then channel should not use Broadcast to directly send messages instead only firing the appropriate events