Bug Fixes - autofilter

- Auto filter now only creates a filter for read-only commands.
- Fixed bug whereby ambiguities were reported twice:
    "could be one of a, b, a, b".

src/Context.h

@@ -58,7 +58,7 @@ public:
 private:
   void loadCorrectConfigFile ();
   void parse ();
-  void constructFilter ();
+  void autoFilter ();
 
 public:
   Config                    config;