[Pd] Messages to windows

[Chuckk Hubbard]

That would be useful.  Also would be useful if, instead of just
printing "no such object" when there isn't one, there could be some
sort of bang to indicate this, so that object can be created if
necessary.

> who is in charge about coordinating tcl/tk and pd? only Mr. Puckette? I
> guess that an option to query objects for their parameters would really
> speed up and enhance interface design in pd. something like "; myhslider
> get_width". currently it can only be used to get the coordinates of a
> canvas.