Some cameras may offer resolutions too high for textures

When testing on the Lumia 1520, the rear camera was found to offer resolutions too high for texture streaming, as D3D could not make a texture with such a high resolution.

Providing the QCameraViewfinderSettingsControl would solve the problem by allowing the system to default to the lowest resolution, but let the user try something higher.

It's also worth investigating blitting with different source/target resolutions, and possibly transforms.