A temporary note on machine vision with ML Kit and Flutter

1. Firebase ML Kit is deprecated (https://developers.google.com/ml-kit/migration). All 3rd-party published tutorials I could find on September 6, 2020 are referring to the deprecated APIs.

2. As of June 3, 2020 the new products / APIs are ML Kit (https://developers.google.com/ml-kit) and Firebase Machine Learning aka Firebase ML, in beta (https://firebase.google.com/products/ml).

3. Flutter (https://flutter.dev/) features a plugin from the Firebase team named `firebase_ml_vision`, described as "A Flutter plugin to use the capabilities of Firebase ML, which includes all of Firebase's cloud-based ML features, and ML Kit, a standalone library for on-device ML, which can be used with or without Firebase" (https://pub.dev/packages/firebase_ml_vision). 
Thus the plugin is supposed to cover both ML Kit (which can be used without Firebase) and Firebase ML. Its name therefore could lead to confusion.

4. As of September 6, 2020, the plugin, however, does not work with the new **ML Kit**. Also the instructions describe the deprecated **Firebase ML Kit** (https://github.com/FirebaseExtended/flutterfire/issues/3473). 

5. To use any pretrained ML Kit on-device (bundled or download via Play Services) model such as Face Detection with ML Kit, one should be able to use the plugin without setting up a Firebase project. This example for the native Android version of ML Kit shows how: https://github.com/googlesamples/mlkit/tree/master/android/vision-quickstart. 

6. Things seem to be in heavy flow at Google. It certainly has a "20 product managers in a room with a knife" vibe. Or there is just confusion about how to deal with the machine learning part / ML Kit. For more context read: https://medium.com/flutter/updates-on-flutter-and-firebase-8076f70bc90e, look at the table here: https://firebase.flutter.dev/ and the documentation here: https://firebase.flutter.dev/docs/overview. What would Sherlock Holmes do?

7. I will therefore update this note until it itself is deprecated.