Kraken: mark a vj as "stay_in" if the next section is a transfer of type "stay_in"
Kraken: Fill the from and to in section even if there is only 1 stop_point

This case happen on "extension of service" (also known as stay in
transfert) when the passenger has to board on the last stop point of a vj
Kraken: add test on stay_in with boarding at terminus
Merge pull request #520 from kinnou02/stayin

improvement of stay in connection