Update nlohmann/json adapters

Author: d-frey

contrib/nlohmann.cpp

@@ -16,8 +16,8 @@ namespace tao
    {
       void unit_test()
       {
-         tao::json::nlohmann::to_value value_consumer;
-         tao::json::events::from_string( "[ null, true, false, 42, 43.0, \"foo\", [ 1, 2, 3 ], { \"a\" : \"b\", \"c\" : \"d\" } ]", value_consumer );
+         tao::json::nlohmann::to_value<::nlohmann::json > value_consumer;
+         tao::json::events::from_string( value_consumer, "[ null, true, false, 42, 43.0, \"foo\", [ 1, 2, 3 ], { \"a\" : \"b\", \"c\" : \"d\" } ]" );
 
          const auto& v = value_consumer.value;
 
@@ -40,7 +40,7 @@ namespace tao
          TEST_ASSERT( v[ 7 ].at( "c" ) == "d" );
 
          tao::json::events::to_string output_consumer;
-         tao::json::nlohmann::from_value( v, output_consumer );
+         tao::json::nlohmann::from_value( output_consumer, v );
 
          TEST_ASSERT( output_consumer.value() == "[null,true,false,42,43.0,\"foo\",[1,2,3],{\"a\":\"b\",\"c\":\"d\"}]" );
       }

contrib/nlohmann/from_value.hpp

@@ -16,8 +16,8 @@ namespace tao
       {
          // Events producer from an nlohmann/json value.
 
-         template< typename Value, typename Consumer >
-         void from_value( const Value& v, Consumer& consumer )
+         template< typename Consumer, typename Value >
+         void from_value( Consumer& consumer, const Value& v )
          {
             switch( v.type() ) {
                case Value::value_t::discarded: