Multi-window mode

[jasonhocker]

Update the diagram with the quarks introduced with multi-window mode to the lifecycle. Such as the recommendation to have video apps handle playback play/pause in onStart/onStop instead of onResume/onPause

[milosmns]

Multi-window mode will just call pause-stop-destroy-create-start-resume-**pause** when going into the split screen, and pause-stop-destroy-create-start-resume-**pause**-**resume** when going out of it. That doesn't affect the lifecycle in any way, it just recreates the whole activity from scratch.

[TomMannson]

Some update needed:
There are new assumptions presented on Google IO when more then one Application can be in resumed state at same time.
https://youtu.be/8uQEzv3upy8?t=706