Also:
- use '/usr/bin/env python' to easily use a Python interpreter different than
  /usr/bin/python
- demo must be run by root so "dont_write_bytecode" to avoid having *.pyc files
  owned by root in the working copy

This is then easier to restart it manually.

This is a workaround waiting that we have better criteria to select tunnels
to create or destroy.

UDP protocol is useless if nothing is done to prevent fragmentation.
Otherwise, it is at best unefficient.

There exist routers on the internet that filter fragmented packets with specific
data. This is hard to debug because TCP connections hang randomly when there is
no OpenVPN encryption.

Now, only TCP is enabled by default. A second protocol should be there for
better performance when possible, either existing UDP one (provided it is
guaranteed there is no fragmentation) or something better (GRE ?).

This reverts commit 7dbc38d7.

Fixed upstream in version 0.2
See also http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=725344

The way peer addresses were exchanged polluted caches with information about
dead nodes. In particular, bootstrapping often took a long time because the
cache of the primary node was mostly useless.

This also fixes bootstrap of registry.

This is a common misconfiguration that may break internet acces for other peers.

We also stop checking for child process termination when used without tunnel
manager (i.e. with --client or --client-count=0) because it conflicts with the
'ip route' command that is called every minute if --table=0 is used.
Anyway, with a tunnel manager, only openvpn client are watched.

- authenticated communications with registered clients
- XML-RPC is dropped
- multi-threaded server

This replaces --connection-count, for more customization, but without requiring
more configuration from the user.

The previous broadcast model is replaced by a query-response one.
During normal operation, the cache of peers is not used anymore to select
peers to connect to. It now only used for bootstrapping and avoid querying
an already known address.

Co-written with Ulysse