It's a bit awkward, but to generate a page needed to update
BoostPages_Page, which wasn't always appropriate. So now generate pages
just using the data from the quickbook source, combined with the state
data.
Main change is that 'unversioned.qbk' now has null release_data. Will
result in a change to the qbk_hash, but I'll manually handle that. This
means that its no longer a 'release' but still want it to appear on
history page.
