Better null-tag handling; integrate CSaveWorld and CMapWorld loading

Runtime/AutoMapper/CMapWorld.cpp

@@ -2,6 +2,11 @@
 
 namespace urde
 {
+
+CMapWorld::CMapWorld(CInputStream& in)
+{
+}
+
 u32 CMapWorld::GetNumAreas() const
 {
     return x0_areas.size();
@@ -81,4 +86,10 @@ void CMapWorld::ClearTraversedFlags() const
 
 }
 
+CFactoryFnReturn FMapWorldFactory(const SObjectTag& tag, CInputStream& in, const CVParamTransfer& param,
+                                  CObjectReference* selfRef)
+{
+    return TToken<CMapWorld>::GetIObjObjectFor(std::make_unique<CMapWorld>(in));
+}
+
 }