* Add generalised error reporting framework:

err :: FilePath -> Int -> String -> String -> IO ()

Then any call to err makes all commands fail. Means that something like check
can just compose things and check for error.

* Fix bibtex so it runs enough times after paper.aux changes

* Add paper check

Run all checks in parallel

* Update paper haskell

* Add paper bibtex

* Add paper overfill hbox

* Add a manual