(svn r8626) [0.5] -Backport from trunk (8294, 8296, 8536, 8540, 8609):
-Fix: deleting a vehicle with shared orders, but no orders would fail to reset prev_shared and next_shared
-Fix: GenerateVehicleSortList()/CmdMassStartStopVehicle() tried to put a TileIndex into an uint16
-Fix (FS#577): Road Vehicles now can obtain a slot even if the station is very spread out
-Fix[YAPF]: Assert when buoy is placed on NE or NW map edge (Dan)
-Fix: a road vehicle that is very close after another (slower) road vehicle gets its speed reset to 0 when entering a tunnel, which causes a traffic jam outside of the tunnel.