Kraken: only do crowfly if the used stop point is in the requested area

So if the journey start from a stop_point from another stop_area than
the requested, we display a streetnetwork section
Jormungandr: for crowfly section we don't create a geojson
Kraken: refactoring for add test on "use_crow_fly"

Add some forward declaration in raptor API, so I have to add header in a
lot of files
Kraken: add test on use_crow_fly
Merge pull request #515 from kinnou02/crowfly

Only do crowfly if we leave the requested area