A3t::findAttribute

- FindAttribute implemented, supporting pseudo- and uda- attribute recognition,
  which is an improvement.
- Fully parsed arguments are now locked against further parsing.
- Validation consists of looking for unlocked args.
- Added more entities for testing.
- Updated test script.

src/parser/A3t.h

@@ -49,6 +49,7 @@ private:
   void findPattern ();
   void findSubstitution ();
   void findTag ();
+  void findAttribute ();
   void validate ();
 
 private: