Merge pull request #80 from xamarin/add-license-1

Create LICENSE

Improve ARKit face demo

Update README.md

Update README.md

fix arkit demos

update samples to 1.8.71

Update README.md

Update README.md

Update README.md

fix Mixed/AR/iOS launcher

Add Mixed AR sample: ARKit + ARCore + HoloLens

Add ARKit sample

fix Cocoa sample

Update samples to 1.8.51