Add option to node bindings to return result as a pre-generated JSON string (this avoids a lot of overhead, and moves JSON string rendering out of the main event loop).

include/util/json_container.hpp

@@ -81,6 +81,19 @@ struct String
     std::string value;
 };
 
+/**
+ * Typed string wrapper.
+ *
+ * Unwrap the type via its value member attribute.
+ */
+struct Buffer
+{
+    Buffer() = default;
+    Buffer(const char *value_) : value{value_} {}
+    Buffer(std::string value_) : value{std::move(value_)} {}
+    std::string value;
+};
+
 /**
  * Typed floating point number.
  *