Functionality unchanged
Internal refactor: create onClickListener and ReactionTime observer (support library) fragment - static inner class StatusAreaFragment. This fragment is now responsible for hosting the ReactionTimer instance and updating the reaction time and score. It also listens to the Main Activity's button. The main activity doesn't do much at this point.
The purpose of the refactor is to learn more about the fragment lifecycle and (next step) setRetainInstance to true and allow orientation changes to see if the test continues normally.
Cleanup some commented out code in ReactionTimer (commit to refactor).
Fragment setRetainInstance(true) and removed android:orientation="locked" from manifest but operation is quirky. There seems to be some difficulty getting the status views after the activity is destroyed and recreated due to an orientation change. Why?? The views are part of the fragment, not the activity so shouldn't be destroyed and in any case I am not caching the views but rather using getView().findViewbyId().
For this commit I am keeping setRetainInstance(true) but I restored the orientation lock until I can experiment some more.