All QObject output values are now wrapped in to QJSValues and
input QObject values are treated as QJSValues. Id property removed
from the Program3D object as that shouldn't be exposed to the JS side.

Change-Id: I424ec946554150e06adb30bff8be968ec832e998
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>

Change-Id: Ib1ada2b821c574333f726b7228c430876a49856a
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>

All JavaScript visible objects are now based on QQmlPropertyMap so that libraries and other users can add dynamic properties to the objects like they do in many cases. Also fixed textured cube example to respect devicePixelRatio.

Change-Id: I71a8d8e32e2d856dc1c97f498c9a34b3858ab6a9
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>

Also fixed some of the potential null pointer issues if using shader methods on deleted shader objects.

Change-Id: Ied254c1f96f283ba2f48f5a453c38bb7d7981a60
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>