Hairy select changes ohoy

[Lars Magne Ingebrigtsen <larsi@gnus.org>]

I've had to rework the thing that tries to uniquify the servers a bit.
It's hairy, hairy code, and I'm not all that comfortable tampering with
it, but it has to be done.

The upshot of it all is that if you have, say, 100 groups where the
first has this method:

(nnfolder "archive" (nnfolder-expire t))

and 99 groups with this method:

(nnfolder "archive" (nnfolder-expire nil))

then Gnus would create 100 different select methods, and call
*-request-open on each server.  This is most dramatic with nnimap
servers, where you get 100 tls connections set up, which takes...  a
while.

The change I've done tries to do the logical thing -- create two
servers.  This works for me in my test cases, but...

Give it a whirl.

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@gnus.org * Lars Magne Ingebrigtsen