The current code base isn't mature enough to be merged into the main branch. Some of the techniques aren't stable and the code also changes OGRE itself, rather than being a standalone demo as intended. The changes to OGRE's core make merging this in non-trivial. I haven't had the time to do this properly.
Ideally, I think most of the changes to OGRE's core can be refactored to be truly an extension and not a modification, making this a demo that can easily fit with ogre. This isn't the case. If someone was to do this we would be very grateful.