first draft of new pdgui interface using a small callback-based framework

Some reference to patchwin remain...
This refactors pdgui.js to prevent errors for early messages from Pd.
Some references to raw patchwin array still remain, but on the whole this
should make things more sane.

There might also still be some places where a null-dereference error will
still bite us. For example, I think we need a check in the "q" method for
existence. But such changes can now happen in a single location inside
the "gui" definition, rather than scattering them throughout the file as
was done before as a stopgap.