Routing: add test with originmode=bike and destination=walk

And you have a direct path with bike
Kraken: Change behaviour of direct path

If modes are different we try to find a path with the origin's mode
Kraken: move building of direct path

We may change the arrival path finder, so we need to do it after
building  paths
Kraken: fix a bug to really start the dijkstra

Add a function start_dijkstra_distance to start the dijkstra without the
need of a proximity list
Kraken: compute direct_pathes even when no stop_points are found
Jormungandr: Keep only one car journey
Merge pull request #480 from l-vincent-l/always_do_direct_path

Always do direct path