2.8

Large release with several major changes:

• let operators for OCaml >= 4.08
• deprecate {of,to}_seq in favor of {of,to}_iter
• deprecate CCKList in favor of Seq.t (and add {of,to}_std_seq where possible)
• a lot of new functions for lists
• use a tiny bit of unsafe in CCVector to prevent it from keeping values alive for too long
• fixes related to mdx and dune 2

detailed changelog