Bug Fix - #252

- Fixed bug that prevented using end.after: and end.before: together
  to effect a range.
- Required differentiation between positive and negative attribute
  modifiers, and special handling.

src/Att.h

@@ -50,6 +50,7 @@ public:
   static bool validNameValue (std::string&, std::string&, std::string&);
   static bool validMod (const std::string&);
   std::string type (const std::string&) const;
+  std::string modType (const std::string&) const;
   void parse (const std::string&);
   void parse (Nibbler&);
   bool match (const Att&) const;