(svn r18404) -Codechange: link drive through stops better together

-Feature: make penalty for road stop occupancy user configurable
-Fix [FS#1944]: road vehicles would not pick an empty drive through stop. Now they will *if* the penalty for driving around is less than the occupancy penalty
-Fix [FS#1495]: long (articulated) road vehicles could block loading of others when the following road vehicle already got 'permission' to go to the next bay even when it could not reach it
-Change: improve the throughput of the drive through road stops by letting them stop closer together

src/saveload/station_sl.cpp

@@ -15,6 +15,7 @@
 #include "../roadstop_base.h"
 #include "../vehicle_base.h"
 #include "../newgrf_station.h"
+#include "../station_map.h"
 
 #include "saveload.h"
 #include "table/strings.h"
@@ -108,6 +109,25 @@ void AfterLoadStations()
 	}
 }
 
+/**
+ * (Re)building of road stop caches after loading a savegame.
+ */
+void AfterLoadRoadStops()
+{
+	/* First construct the drive through entries */
+	RoadStop *rs;
+	FOR_ALL_ROADSTOPS(rs) {
+		if (IsDriveThroughStopTile(rs->xy)) rs->MakeDriveThrough();
+	}
+	/* And then rebuild the data in those entries */
+	FOR_ALL_ROADSTOPS(rs) {
+		if (!HasBit(rs->status, RoadStop::RSSFB_BASE_ENTRY)) continue;
+
+		rs->GetEntry(DIAGDIR_NE)->Rebuild(rs);
+		rs->GetEntry(DIAGDIR_NW)->Rebuild(rs);
+	}
+}
+
 static const SaveLoad _roadstop_desc[] = {
 	SLE_VAR(RoadStop, xy,           SLE_UINT32),
 	SLE_CONDNULL(1, 0, 44),