Seems like RNNSplitViewOptions wasn't updated to use the presenters, so
the options were going nowhere.

* Work in progress

* Arbitary changes

* Improvements on API

* Cleanup RNNSplitViewController, allow mergeOptions

* Added documentation and better playground example

* Adding tests for coverage

* Find out why this test is failing.

* Only show split view on iOS

* Add test back in