Fix for scaled images. Request to break freeze.

[Jasper Huijsmans]

Hey Olivier,

Because of the continuing problems with the scaled images I decided to
finally implement that scaled_image widget that I should have used from
the start. In this way, you can scale the image using the actual size
allocated to it, instead of trying to figure out border sizes and other
style properties from the parent containers.

I changed the iconbutton and menubutton to use it and it seems to work
fine. The implementation is almost identical to the ones in iconbutton
and menubutton now, so I don't expect a problem.

Now, on to the tricky part, we are in freeze for 4.0. I would like this
fix to go into the release, but I can certainly live with the current
situation.

To test, download from here:

http://members.home.nl/xfce4/files/libxfcegui4-cvs.tar.bz2


Let me know what you think.

	Jasper