Fix demo project
SwiftFormat

Move environment keys to be direct modifiers (work around Swift compiler bug in 5.2)
- this has the advantage of making the modifiers specific to collectionView vs tableView

* `onReachedBoundary` support
* Implement DataSource support for RandomAccessCollection (allows use of FetchedResults directly)
* Improve initial loading of data

* Add 'shouldInvalidateLayoutOnStateChange' setting, with option for disabling/enabling animation
* Add AdjustableLayout screen in demo project

Fix #42 

- Renamed demo screens