Allow network login over secured network

[Bruno Tavernier <tavernier.bruno@gmail.com>]

Here is the story:

When one is behind a proxy with limited access (i.e. http and https) it
is sometime convenient to create some ssh tunnels to reach freedom. In
our case, mails and news server. ;-)

In such a case, the connection being already secured by ssh, it makes
sense to simply login with for instance (nnimap-stream network).

I guess the performance hit of a double layer of encryption (ssh+tls) is
no huge, but still.

However, with the commit below, connecting over ssh to starttls capable
server automatically upgrade "network" to "starttls".

2010-09-30  Lars Magne Ingebrigtsen

	* nnimap.el (nnimap-open-connection): Reinstate the auto-upgrade from
	unencrypted to STARTTLS, if possible.


Would it be possible to do something like:

Gnus default option -> "starttls" (as its seems to be the favored method
 and plain text connection is *bad*)

When user wants to use "network", well, if they set the option they know
what they're doing (or let's hope so). :-)


-- 
Bruno