Remove transport pointer from ssl and sasl structs
- This involved changing pn_ssl_init() API
Reorganise layer initialisation:
- Defer until first send/receive
- Move layer initialisation entirely to transport
Mostly split transport into server/client sides
WIP
WIP: A lot of server autodetection done - not fully working yet
WIP: Somewhat working server autodetect - passes tests now
- There seems to be an issue if autodetecting ssl and the
  handshake failing that ssl isn't fully destroyed.
WIP: add enough to ssl_stub to make us compile without ssl
WIP: Make windows driver compile
WIP: Make schannel ssl impl compile - it hangs though