Added an iterator class that can iterate through both sequence and map nodes.

scalar.h

@@ -14,6 +14,15 @@ namespace YAML
 		virtual void Parse(Scanner *pScanner, const ParserState& state);
 		virtual void Write(std::ostream& out, int indent);
 
+		// extraction
+		virtual void Read(std::string& s);
+		virtual void Read(int& i);
+		virtual void Read(unsigned& u);
+		virtual void Read(long& l);
+		virtual void Read(float& f);
+		virtual void Read(double& d);
+		virtual void Read(char& c);
+
 	protected:
 		std::string m_data;
 	};