Added support for hidden options through subclassing Option class.

options.h

@@ -260,6 +260,13 @@ namespace Utilities {
     unsigned int valuevec_size_;
   };
 
+  template<class T> class HiddenOption: public Option<T>
+  {
+  public:
+    HiddenOption(const string& k, const T& v, const string& ht,
+		 bool c, ArgFlag f = no_argument): 
+      Option<T>(k, v, ht, c, f), { visible_ = false; }
+  };
 
   /**
      A class for parsing command line arguments into Option objects. The