[PATCH]shortPathfinder may return paths in non passable region.
There is a defect in the short pathfinder when dealing with obstructions. It can enter inside the obstruction and then continue its path in non passable regions. This is easily reproducile with a dock. Putting a unit along the dock, at the limit of the water and asking it to go just a few meters (smaller than the short/long separation) inside the water. The short pathfinder will make it go round the dock. Same thing with a ship and ask it to go a few meters in the land. This is one of the reasons for bugs as #3472 because as soon as there is a dock around, ship movements become completely crazy due to this problem. The patch attached is a (hacky) fix.