add containers.pp sublibrary, with Wadler-style pretty printing combinators

add CCArray.{max,argmax,min,argmin} and their _exn counterparts

add CCParse.take_until_success

add Option.flat_map_l

add CCSet.{find_first_map,find_last_map}

CCHash: native FNV hash for int64/int32

fix bugs in CCParse related to recurse and Slice

fix: fix Set.find_last_map on OCaml 4.03

fix: make sure Vector.to_{seq,gen} captures the length initially