Introduce a get_instance factory method for all plugins and other xmpp related classes. This will help us to decouple plugs in order to make them testable.

Proposed Fix. Make sure we read all data from our SSL socket wrappers and don't just rely on gobject.io_add_watch, select or poll.

This isn't really a clean solution, but the less intrusives fix that I can think of. Fixes #2634.

  Gajim will do HTTP CONNECT on proxy to reach the BOSH Conn manager and try
  to estabilish TLS (same as what firefox do when approaching HTTPS server via
  proxy)
- moved proxy-connecting code to xmpp/proxy_connectors.py
- debugged SOCKS5 proxy code
- tested with Tigase server

  derived (was plugged to NonBlockingClient which made it unusable for BOSH)
- Fixed HTTP CONNECT proxy socket
- Implemented workaround for the bug with insecure-connection warning dialog
  (unfortunately, this is not over - I just forbid the transport to send
  BOSH empty bodies until auth module is plugged, which is wrong and will
  break if user will wait more than "inactivity" (usualy thirty) seconds
  before clicking the dialog.
  This workaround works with ejb and opf, and also breaks connection with
  both of them if delay is too long.
- Implemented basic TLS over BOSH. It works only with OPF and poorly.

we have that in all files. To at least lesser the confusion a bit, add
vim tags for that.
Additionally, fix wrong #! in a few files.

- improved HTTP persistent connections
- added alarm-unregister method to idlequeue
- extended proxy managing dialog for BOSH proxy

persistent HTTP connections in BOSH roughly implemented, added hack for openfire incapability of after-SASL-stream-restart-response in BOSH, changed doubles quotes to single

BOSHClient transformed to NonBlockingBOSH transport - it's easier to maintain more connections from below, implemented handling of non-persistent HTTP connections - it runs with ejabberd, improved NonBlockingTransport interface, minor changes in BOSHDispatcher

new BOSHDispatcher (in dispatcher_nb), improved BOSHClient class, minor changes in other xmpp modules