[sugar] new toolbar API in Sugar

[Tomeu Vizoso]

Hi all,

we've added some new classes to the sugar.graphics package in order to
have toolbars in activities that match a common look&feel. Activities
should use this classes instead of the toolbar and buttons in gtk.

The web activity has already been ported to use this API, but perhaps
it's easier to refer to the example in here:
http://wiki.laptop.org/go/Sugar_Code_Snippets

The idea is to add there new controls/widgets based on hippo that can be
reused in all activities present and future (so as always, think about
the children when deciding the API).

We're going to develop further this UI class library during the
development of the Journal, so during B3 will be a good moment to give
suggestions.

Thanks,

Tomeu