This patch integrate the scout widgets with Genode's new API headers
'util/geometry.h', 'os/surface.h' and 'os/texture.h'. Thereby, we get
almost rid of the platform-abstraction shim that was never used anyway.
Furthermore, it extracts the parts that are worth reusing from the
scout implementation to the public location 'demo/include/scout'.
With this patch, 'liquid_framebuffer' can be reconfigured at runtime.
The configuration arguments are now provided as XML attributes, matching
those for 'nit_fb'. Furthermore, two new configuration options are added:
<config ...
resize_handle="off" - show/hide a resize handle widget in the lower
right window corner
decoration="on" - show/hide window decoration
(title bar and borders)
/>
Fixes#740Fixes#14
