Enhancements - Nibbler + parsing

- New Nibbler object greatly assists in FF4 parsing.
- Unit tests for Nibbler.
- Record now parses itself.
- Att now parses itself.

src/Att.h

@@ -29,6 +29,7 @@
 
 #include <string>
 #include <vector>
+#include "Nibbler.h"
 #include "Mod.h"
 
 class Att
@@ -41,7 +42,7 @@ public:
   Att& operator= (const Att&);                  // Assignment operator
   ~Att ();                                      // Destructor
 
-  void parse (const std::string&);
+  bool parse (Nibbler&);
   std::string composeF4 () const;
 
   void addMod (const Mod&);