In recent versions of libpqxx the pqxx::prepare::treat_string has been removed.

Please validate this code works as expected.
ed: support pqxx v3 and v4

As pqxx::prepare changed in pqxx v4 and that we need to support pqxx v3 because v4
is not yet in Debian stable, we check the pqxx version with the preprocessor.

fix #301.
Merge pull request #514 from TeXitoi/libpqxx4

ed: support pqxx v3 and v4
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