Fix ship collision avoidance near docks when dock not under station sign

See #77

src/ship_cmd.cpp

@@ -647,7 +647,13 @@ static bool HandleSpeedOnAqueduct(Ship *v, TileIndex tile, TileIndex ramp)
  */
 static void CheckDistanceBetweenShips(TileIndex tile, Ship *v, TrackBits tracks, Track *track_old, DiagDirection diagdir)
 {
-	if (DistanceManhattan(v->dest_tile, tile) <= 3 && !v->current_order.IsType(OT_GOTO_WAYPOINT)) return; // No checking close to docks and depots.
+	// No checking close to docks and depots.
+	if (v->current_order.IsType(OT_GOTO_STATION)) {
+		Station *st = Station::Get(v->current_order.GetDestination());
+		if (st->IsWithinRangeOfDockingTile(tile, 3)) return;
+	} else if (!v->current_order.IsType(OT_GOTO_WAYPOINT)) {
+		if (DistanceManhattan(v->dest_tile, tile) <= 3) return;
+	}
 
 	Track track = *track_old;
 	TrackBits track_bits = TrackToTrackBits(track);

src/station.cpp

@@ -318,6 +318,15 @@ bool Station::IsDockingTile(TileIndex tile) const
 	return false;
 }
 
+bool Station::IsWithinRangeOfDockingTile(TileIndex tile, uint max_distance) const
+{
+	if (DistanceManhattan(this->xy, tile) > _settings_game.station.station_spread + max_distance) return false;
+	for (const Dock *d = this->docks; d != NULL; d = d->next) {
+		if (DistanceManhattan(d->GetDockingTile(), tile) <= max_distance) return true;
+	}
+	return false;
+}
+
 /** Rect and pointer to IndustryVector */
 struct RectAndIndustryVector {
 	Rect rect;                       ///< The rectangle to search the industries in.

src/station_base.h

@@ -515,6 +515,7 @@ public:
 	}
 
 	bool IsDockingTile(TileIndex tile) const;
+	bool IsWithinRangeOfDockingTile(TileIndex tile, uint max_distance) const;
 
 	/* virtual */ uint32 GetNewGRFVariable(const ResolverObject &object, byte variable, byte parameter, bool *available) const;