New window configuration syntax

[Lars Magne Ingebrigtsen <larsi@ifi.uio.no>]

I think we'll call it `gnus-frame-configuration' this time.  :-)

I don't remember who came up with the syntax, but it's pretty neat and
easy to work with:

CONFIG ::= (SPLIT ...)
SPLIT ::= (horizontal size SPLIT ...) |
          (vertical size SPLIT) |
          (buffer size [point])

So it's a recursive structure inside each frame.  (Each SPLIT in
CONFIG is a separate frame.)  *All* thinkable window configurations
are possible.  (Unless you're a person who thinks the unthinkable.) 

So now we have `gnus-frame-configuration', `gnus-buffer-configuration'
and `gnus-window-configuration', in order of presedence.
Uhmn... perhaps I'll just ditch `gnus-buffer-configuration'.  It's
easy enough for users to translate a `gnus-buffer-configuration' into
a `gnus-frame-configuration'.

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@ifi.uio.no * Lars Ingebrigtsen