Squashed 'sequence/' content from commit e5625c6

git-subtree-dir: sequence
git-subtree-split: e5625c69301e344abb971ad47ba618387346dc22
Merge commit 'c8d834b722a95b9feedf17f91511d138662c6d6f' as 'sequence'
CCSequence now shares code with the 'sequence' library; merged the .mli so it reflects versions properly