Implement ARImageTrackingConfiguration

[aferriss]

Implement a new session configuration for ARImageTrackingConfiguration.

This new configuration tracks the world based on recognizing images rather than by observing device motion etc. The advantage of this seems to be that it's much faster, and you could potentially track a whole bunch of images all at once. The downside is that they have to be in front of the camera. This mode can only orient the device in the world if the camera can see a known reference image. Another upside to this that apple mentions is the ability to do AR inside of moving environments like train cars or airplanes.

Another property has also been added to the normal world tracking configuration, as well as this new one for capping the maximum number of tracked images. Probably not that important but worth documenting anyway.

My guess is that this feature is probably one of the easier ones to implement out of the ARKit 2.0 features, especially since some of this functionality has already been implemented in the most recent ofxARKit.

Lastly another unity video showing this in action