* Fix iOS 10 specific documentation
* Fix typos/spelling-errors

Prevent NullPointerException if application activity is singleTop and minimized/restored from launcher icon. (#108)

In that case activity is reused and intent.getExtras() returns null.

* Add firestack header search paths

If users have installed firestack, modules may live here instead.
Include them just in case.

* Include firestack paths to frameworks

* Import Firebase via module

* Ignore xcuserdata