No reason to have this kind of stuff in two different places.

There's nothing important in here anymore, and we need to condense these lists
into one central place.

This is to draw the user's attention to them a little better.  It also allows
me to kill all that CSS provider crud, which it turns out isn't even needed.
This probably changed when I started using the PangoAttrList.

Doing it from the init method means we need to call gtk_widget_realize so all
the gdk and cairo stuff has something to operate on.  However, that realize
call screws up glade so that the window gets displayed separately and widgets
cannot be clicked upon.

This reorganization moves the gradient setup to after the widget has been
realized.

The idea here is that by adding a gradient up top, the "Done" button looks
more like it belongs with the header than with the widgets down in the
spoke.  It also subtly makes the spoke look like a subpart of the hub.

Adding this required adding an additional internal widget, which means also
changing all existing glade files to include this internal widget.  Make sure
to build new glade support and install locally (or use the proper makefile
targets) before editing.

Except on the hub, which is special and is going to need special work done
for it.