Connect fixes

Fixes for connection hangs and crashes (#60)

* A connection which is already disconnected in shutdown should try to reconnect, because that means it was hung up on

* channel shutdown complete event must ALWAYS be called from channel shutdown callbacks

* If the socket was connected, go into the reconnect cycle

* Re-worked reconnect detection logic

* Ensure that on_connection_complete is called for the first completed connection, even if it's a reconnect

* documented connection_count