Add TClass::ObjectPtr default constructor.
Add TClass::ObjectPtr default constructor.

But keep the explicit/long calls with core/meta for clarity

olifre/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root