Some notes about the various tables

channels:

	Normally a channel is short (20 char).
	But channels are used for messages. In this case, a channel name can be very long since it
	represent the list of users in the conversation.

	This is why name is a varchar.

	The field deleted allow the channel to exist even if it is deleted (and potentially being undeleted).
	The channelid may continue to exist in the table dirs_content.