Carousel: make it possible to use it inside another swipeable element (#152)

Author: balat

src/widgets/ot_carousel.eliom

@@ -387,7 +387,10 @@ let%shared make
            then Stopped (* swiping in wrong direction (vertical/horizontal) *)
            else
              if abs move > Ot_swipe.threshold
-             then begin
+             then begin (* We decide to take the event *)
+               (* We send a touchcancel to the parent
+                  (which received the start) *)
+               Ot_swipe.dispatch_event ~ev d2' "touchcancel" (clX ev) (clY ev);
                Manip.Class.add ~%d2 ot_swiping;
                set_top_margin ();
                remove_transition d2';

src/widgets/ot_swipe.eliomi

@@ -31,3 +31,7 @@ val bind:
 val clX : Dom_html.touchEvent Js.t -> int
 val clY : Dom_html.touchEvent Js.t -> int
 val threshold : int
+val dispatch_event :
+  ev:Dom_html.touchEvent Js.t ->
+  Dom_html.element Js.t ->
+  string -> int -> int -> unit