(svn r17552) -Codechange: rename load_unload_time_rem to something more generic as it's used for more than just load/unload. Also add some documentation about where it is used.

src/vehicle.cpp

@@ -966,7 +966,7 @@ void VehicleEnterDepot(Vehicle *v)
 			if (_settings_client.gui.show_track_reservation) MarkTileDirtyByTile(t->tile);
 
 			UpdateSignalsOnSegment(t->tile, INVALID_DIAGDIR, t->owner);
-			t->load_unload_time_rem = 0;
+			t->time_counter = 0;
 			ClrBit(t->flags, VRF_TOGGLE_REVERSE);
 			TrainConsistChanged(t, true);
 			break;