cleanup: silence our own React dev-console warnings

UNSAFE_ rename of our 4 componentWillReceiveProps (FireStats, Fires, FromNow,
SelectionMap) and Authenticated/Public component propType func -> elementType.
Rest of the console noise is legacy react-* dev-mode warnings, absent in prod.

imports/ui/components/Public/Public.js

@@ -21,7 +21,7 @@ const Public = ({
 Public.propTypes = {
   loggingIn: PropTypes.bool.isRequired,
   authenticated: PropTypes.bool.isRequired,
-  component: PropTypes.func.isRequired
+  component: PropTypes.elementType.isRequired
 };
 
 export default Public;