Structure of a session:

session {

	-- properties --

	conn -- the tcp connection

	notopen -- true if stream has not been initiated, removed after receiving <stream:steam>

	priority -- the resource priority, default: 0

	type -- the connection type. Valid values include:

			-- "c2s_unauthed" - connection has not been authenticated yet

			-- "c2s" - from a local client to the server

	username -- the node part of the client's jid (not defined before auth)

	host -- the host part of the client's jid (not defined before stream initiation)

	resource -- the resource part of the client's full jid (not defined before resource binding)

	-- methods --

	send(x) -- converts x to a string, and writes it to the connection

}