New contract in CameLIGO, based on the tutorial. (Not called from the CI.)

src/contracts/incr_decr.mligo

@@ -0,0 +1,20 @@
+type storage = int
+
+(* variant defining pseudo multi-entrypoint actions *)
+
+type action =
+| Increment of int
+| Decrement of int
+
+let add (a : int) (b : int) : int = a + b
+
+let subtract (a : int) (b : int) : int = a - b
+
+(* real entrypoint that re-routes the flow based on the action provided *)
+
+let%entry main (p : action) storage =
+  let storage =
+    match p with
+    | Increment n -> add s n
+    | Decrement n -> subtract s n
+  in ([] : operation list), storage