Improves react-navigation typings
Improves react-navigation typings

magny/DefinitelyTyped,magny/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,borisyankov/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped