examples/quick/window example: fullscreen is possible on OSX

It's normally disallowed without the WindowFullscreenButtonHint.
But if we're going to declare a value for flags, then we have to
put back the Window type which would otherwise be there by default.

Task-number: QTBUG-33607
Change-Id: Ibbd593b2648b98d37c7f70a0b9f96787b0a40f22
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>
Deprecate logicalPixelDensity

It's just not working out in practice, and we don't want to confuse
users with having to pick their flavor of pixel density.

Task-number: QTBUG-34798
Change-Id: I552e479515a6f5249685844143601cb7449ccccc
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>
Remove version definition from custom particle shaders for OpenGL ES.

Since OpenGL ES 2.0 does not support GLSL 1.2, #version 120 must
be removed from embedded shaders for a custom particle.

Task-number: QTBUG-34854
Change-Id: I8d3e51ff87acc099a53c4e312cd33d02e6a1cb4e
Reviewed-by: Alan Alpert <aalpert@blackberry.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Do not crash when one of group animation's children is null

Check if pointer to QQuickAbstractAnimation for which we are setting
group is valid.

Task-number: QTBUG-34851
Change-Id: Iecb549f080804fd9489f884911fa51892def05a5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>