about MODULES and qt2

[Marc Espie <espie@schutzenberger.liafa.jussieu.fr>]

As some of you have noticed, there is some new framework in ports, to
handle subsystems such as qt2 more gracefully (for instance, this should
help the transition to qt3 at some point).

Please note that the interface is not really set in stone. I have no peeve
with ports  using existing MODULES, but make sure you send new module
fragments to me before committing, for now.

Documentation will come as soon as the idea takes a more shapely form.