Merge pull request #1 from struktured/master

add lwt and async style monadic map operators (merge from struktured)
oasis blablabla
move some code to new modules GenClone and GenMList
oasis stuffy stuff
removed obsolete comment
give control over buffering in GenMList.of_gen_lazy
Gen.persistent_lazy now exposes caching parameters related to GenMList.of_gen_lazy
add some more comments
updated .mli to replace "enum" with "gen"
version 0.2.3
add missing @since; expose infix operators
updated doc to make clear that combinators consume their generator argument
markov function