A3t::findTag

- Supports single-word tag add/remove, presence/absence, allowing any non-space
  character in the tag, which is an improvement.

src/parser/A3t.h

@@ -48,6 +48,7 @@ private:
   void findConfigOverride ();
   void findPattern ();
   void findSubstitution ();
+  void findTag ();
   void validate ();
 
 private: