Fix signature of to_string() with indention

Author: d-frey

include/tao/json/to_string.hh

@@ -23,10 +23,10 @@ namespace tao
       }
 
       template< template< typename ... > class Traits >
-      std::string to_string( const basic_value< Traits > & v, const unsigned indent, const unsigned current = 0 )
+      std::string to_string( const basic_value< Traits > & v, const unsigned indent )
       {
          std::ostringstream o;
-         internal::to_stream( o, v, indent, current );
+         internal::to_stream( o, v, indent );
          return o.str();
       }