Everything new in the Android M Preview 2

Ars Technica:

Google pushed out the first update to the Android M Developer Preview. We've already covered the change from 5.1 to Android M Preview 1, so with the new version, we might as well cover the changes between Android M Preview 1 and 2. Google described this release as an "incremental update," and that sounds about right to us—not a whole lot has changed. But hey, we're here, we've got a new version of Android to play with, so lets get comparing!