added option to FastWriter which omits the trailing new line character

include/json/writer.h

@@ -54,6 +54,8 @@ public:
    */
   void dropNullPlaceholders();
 
+  void omitEndingLineFeed();
+
 public: // overridden from Writer
   virtual std::string write(const Value &root);
 
@@ -63,6 +65,7 @@ private:
   std::string document_;
   bool yamlCompatiblityEnabled_;
   bool dropNullPlaceholders_;
+  bool omitEndingLineFeed_;
 };
 
 /** \brief Writes a Value in <a HREF="http://www.json.org">JSON</a> format in a