Introducing opaque type to dmd frontent to be used with certain runtime array

and aa args and returns. There are still some bugs with aas.

gen/typinf.cpp

@@ -128,7 +128,7 @@ Expression *Type::getTypeInfo(Scope *sc)
     }
     }
     e = new VarExp(0, t->vtinfo);
-    //e = e->addressOf(sc);
+    e = e->addressOf(sc);
     e->type = t->vtinfo->type;      // do this so we don't get redundant dereference
     return e;
 }