Default height

Well.. I finally synced my fork and ready to merge back.

- brings `defaultHeight` support (+ per item prediction)
- `didCloack`/`didUncloak` events 
- docs for events and `defaultHeight`
- better structure for README

P.S. Have no idea how to squash all this commits :flushed:
P.P.S. you can do `git merge --squash` from terminal to keep history clean