Correct systemdefn marshalling, add type info for safety

This was causing memory errors with OCaml 5.2.0.
Fixes #116.

src/main.ml

@@ -696,7 +696,8 @@ let process source_filenames =
 let read_systemdefn read_systemdefn_filename =
   let fd = open_in_bin read_systemdefn_filename in
   let sd,lookup ,sd_unquotiented, sd_quotiented_unaux = 
-    try Marshal.from_channel fd 
+    try (Marshal.from_channel fd :
+          (Types.systemdefn * (string -> bool -> string -> Types.symterm list) * Types.systemdefn * Types.systemdefn))
     with Failure s -> Auxl.error None ("Cannot read dumped systemdefn\n   " ^ s ^"\n")
   in
   close_in fd;
@@ -709,7 +710,10 @@ let output_stage (sd,lookup,sd_unquotiented,sd_quotiented_unaux) =
   | None -> ()
   | Some s ->
       let fd = open_out_bin s in
-      Marshal.to_channel fd (sd,lookup,sd_unquotiented) [Marshal.Closures];
+      Marshal.to_channel fd (
+          (sd,lookup,sd_unquotiented,sd_quotiented_unaux) :
+            (Types.systemdefn * (string -> bool -> string -> Types.symterm list) * Types.systemdefn * Types.systemdefn))
+        [Marshal.Closures];
       close_out fd;
       print_string ("system definition in file: " ^ s ^ "\n") );