The Http class is new, it is available on BotLibre.com, but not available in the BotLibre.org open source AI engine yet.
We will hopefully update the GitHub source to version 4.4 soon. For now you can test your script on BotLibre.com
The Self request() API implements the AIML2 SRAIX functionality. In the Bot Libre 4.0 code it can only be used to call other AIML2 compatible services, like forwarding a question to another bot. In 4.4 it will also be able to access XML and JSON web services, and scrape HTML.