[lazarus] ExtCtrls cleaned of GTK code

[Curtis White]

OK, I finally got all the GTK code moved from the TNotebook component to the
gtkint units and it has all been committed to CVS. So now the extctrls.pp unit
does not require the gtk units any more. I also added some additional tests to
the notebook example to test some of the other TNotebook methods and
properties. 

Right now, the TNotebook component has the ability to show tabs,
but to be compatible with Delphi, I will need to remove this ability from the
TNotebook component and add it to the TTabbedNotebook component. But now that I
have the code working with TNotebook, it will just be a matter of moving it to
TTabbedNotebook. So if anyone plans on using the TNotebook component for
anything soon, do not use the tabs properties because they will be moved into
TTabbedNotebook when I get it started and removed from TNotebook. But for now,
they allow you to see that TNotebook is actually working.


Curtis