Clean up the drag and drop code and allow ripping off the Dive Profile

Clean up the drag and drop code and allow ripping off the Dive Profile

Linus had used some deprecated interfcase and didn't correctly untangle
the new window that he created (hiding it the window... very nifty).

I think I'm closer to the real solution with a data structure that keeps
track of the components of the new top level window that I need to be able
to untangle (and eventually, destroy) at the end.

The one error I also can't seem to get rid of is the
Clean up the drag and drop code and allow ripping of the Dive Profile

Gtk-CRITICAL **: IA__gtk_selection_data_set: assertion `length <= 0' failed

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>