DLists: a Haskell list type supporting O(1) append and snoc

Build instructions:

    $ runhaskell Setup.lhs configure --prefix=$HOME
    $ runhaskell Setup.lhs build
    $ runhaskell Setup.lhs install

Running the testsuite:
    $ cd tests && runhaskell Properties.hs

Author:
    Don Stewart
    http://www.cse.unsw.edu.au/~dons