- Introducing NameLookup

  API member functions in Scope:
         Member LookupMember( const std::string & nam ) const;
         Type LookupType( const std::string & nam ) const;

- Using directives
  adding the possibility to add/remove/use using directives
  API member functions in Scope:
         Scope UsingDirectiveAt( size_t nth ) const;
         size_t UsingDirectiveSize() const;
         Scope_Iterator UsingDirective_Begin() const;
         Scope_Iterator UsingDirective_End() const;
         Reverse_Scope_Iterator UsingDirective_RBegin() const;
         Reverse_Scope_Iterator UsingDirective_REnd() const;
         void AddUsingDirective( const Scope & ud ) const;
         void RemoveUsingDirective( const Scope & ud ) const;


git-svn-id: http://root.cern.ch/svn/root/trunk@15376 27541ba8-7e3a-0410-8455-c3a389f83636