Eliom compiler

This is an extension of the OCaml compiler to typecheck Eliom programs. This is WIP.

On .ml programs, the behavior is the same as the normal compiler.

In eliom programs, several extensions are available which are quickly explained here: http://ocsigen.org/eliom/5.0/manual/ppx-syntax

let%server x = 3 (* declaration on the server *)

let%client y = 4 (* declaration on the client *)

let%server z : int fragment = [%client ~%y + 1 ]
(* piece of client code that is manipulated on the server *)

let%client a =
  ~%x (* Injections from the server *)
  + ~%z (* Injections from a fragment. *)