This class implements wrapping methods that allow the engine to be
called even from other APIs or standalone applications.
NOTE: this is a dirty hack and I know it. The problem is that Cocoon is
a servlet and the servlet API are not that easy to deal with when you
enter other modes of operation (like command line or RMI).
We will need to clean this up and remove the need of direct
HttpServletRequest/Response emulation when we integrate with Stylebook.
But I have more important stuff to do right now.