Merge branch 'master' into jgrpp

# Conflicts:
#	CMakeLists.txt
#	bin/ai/CMakeLists.txt
#	bin/game/CMakeLists.txt
#	src/ai/ai_info.cpp
#	src/company_base.h
#	src/economy.cpp
#	src/game/game_info.cpp
#	src/gfx_type.h
#	src/linkgraph/linkgraph_gui.cpp
#	src/palette.cpp
#	src/palette_func.h
#	src/saveload/saveload.h
#	src/saveload/vehicle_sl.cpp
#	src/ship_cmd.cpp
#	src/train_cmd.cpp
#	src/vehicle_base.h
#	src/window.cpp
#	src/window_func.h

src/sl/vehicle_sl.cpp

@@ -564,6 +564,10 @@ void AfterLoadVehicles(bool part_of_load)
 			default: break;
 		}
 
+		if (part_of_load && v->unitnumber != 0) {
+			Company::Get(v->owner)->freeunits[v->type].UseID(v->unitnumber);
+		}
+
 		v->UpdateDeltaXY();
 		v->coord.left = INVALID_COORD;
 		v->UpdatePosition();