(svn r1445) -Fix: reversing a train also reverses the UP and DOWN status for the

realistic acceleration calculation
-Fix: there was a big bug in setting the UP and DOWN flags making it 
easy possible for a overloaded train to go up a mountain. This is no 
longer possible. They will hang at a certain height

vehicle.h

@@ -55,11 +55,11 @@ typedef struct VehicleRail {
 } VehicleRail;
 
 enum {
-	VRF_REVERSING = 1,
+	VRF_REVERSING = 0,
 
 	// used to calculate if train is going up or down
-	VRF_GOINGUP = 2,
-	VRF_GOINGDOWN = 4,
+	VRF_GOINGUP   = 1,
+	VRF_GOINGDOWN = 2,
 };
 
 typedef struct VehicleAir {