Convert aiCamera to cc2DViewportObject

[asmaloney]

Describe the solution you'd like

When reading files that have cameras, convert them to cc2DViewportObjects in CC.

Additional context

Should implement something like this in mioUtils:

ccViewportParameters convertCameraToViewport( const aiCamera *inCamera, const aiMatrix4x4 &inTransform );

and then use it in mioAbstractLoader to create the cc2DViewportObjects.