gEDA-dev: New diagram (attempt at UML)

[Stuart Brorson]

> It thus makes (some) sense to have a "circuit" file, which lists the
> page files making up one circuit. This also makes a good place to put
> toplevel attributes for this circuit.

That was my thought too, but Dan has a different idea and I respect
his views.  This might be worthwhile thrashing out at the code sprint
(or perhaps over IRC earlier).

In any event, to hande the issue of opening a design, it's fairly easy
to have two options for open:

file -> open circuit (design)
   This either opens the additional hierarchy file, or it opens up the
specified .sch file and all subsidiary files which it sources.
file -> open page
   This just opens up the .sch file by itself.

Stuart