simple-egl: fix opaque and 16 bits mode options

In those cases we were writing to the wrong EGL config attribute.

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
desktop-shell: properly set background widget as opaque

Toytoolkit resets the opaque region which was set manually using the
wayland protocol directly, so use the widget API instead.

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
pixman-renderer: free shadow buffer on renderer destruction

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
shell: quit weston, if weston-desktop-shell dies early

If weston-desktop-shell dies soon after launch, or maybe cannot be
executed at all, let weston exit rather than letting the user stare at a
black screen.

But, do not exit weston, if weston-desktop-shell dies later, as the user
may already have apps open, and those apps would likely still function
correctly. This gives the user the opportunity to save his work and
close the apps properly.

This should make one class of "I see only black screen" failures obvious.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Add font entry to shell section for title fonts

cairo-util has used sans font family for title fonts so far.
But sans doesn't support glyphs of non-ascii characters.
So now let users choose a font family for titles.

To show texts correctly now using pangocairo for redering fonts.
If any fonts in 'fonts' entry don't have appropriate glyphs,
we use fallback mode of pango.

This pangocairo support is enabled if configure finds pangocairo
on the build environment.
Otherwise fall back to plain cairo rendering.

The entry name is generic, 'fonts' so that other places
where draw texts can use this entry too.

Signed-off-by: Ryo Munakata <ryomnktml at gmail.com>