Update README/CHANGELOG for release 4.0.0 (#182)

Prepare release

Bump version and prepare release

Merge pull request #146 from s0nerik/s0nerik-npe-livedata

Fixes potential NPE when items are in LiveData

Downgrade AGP to 3.2.0-rc02 for better compatiblity

Downgrade AGP to 3.2.0-rc02 for better compatiblity

Bump version to 3.0.0-beta2 and updated README

Bump version to 2.3.0-beta2

Update README for 2.0.1

Update README.md