Added dataflow module

lib/analysis/Dataflow.mli

@@ -0,0 +1,29 @@
+module type C = sig
+  type elt
+  type internal
+
+  type internalnode = {
+    internalin: internal list;
+    internalout: internal list;
+    internalbetween: internal list list;
+  }
+
+  type cfgt = elt Cfg.cfginternal
+
+  type t = {
+    t: cfgt;
+    internalvar: internalnode Cfg.NodeMap.t;
+  }
+
+  val from_cfg : cfgt -> t
+  val to_cfg : t -> cfgt
+
+  val fixed_point : ?init:(elt list -> internalnode) -> ?update:(t -> Cfg.Node.t -> internalnode) -> t -> t
+
+  val pp : out_channel -> t -> unit
+end
+
+module Make
+    (M: Cfg.PrintableType)
+    (I: Cfg.PrintableType)
+  : C with type elt = M.t and type internal = I.t