[opwig] Adding md::Scope interface.
[opwig] Using Ptr<T> instead of T::Ptr.

Usage:
\#include <opwig/md/ptr.h>

using opwig::md::Ptr;

Ptr<T> var;
[opwig] md::Namespace inherits from md::Scope now.
[opwig] Using final and code alignment.
Merge branch 'md-container' into declaration