Add syntax sugar for lists

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

src/Bergamot/Parser.elm

@@ -74,6 +74,16 @@ term = Parser.lazy (\() -> Parser.oneOf
             , item = term
             , trailing = Forbidden
             }
+    , Parser.backtrackable
+        <| Parser.map (List.foldr (\x xs -> Call "cons" [x, xs]) (Call "nil" []))
+        <| Parser.sequence
+            { start = "["
+            , separator = ","
+            , end = "]"
+            , spaces = Parser.spaces
+            , item = term
+            , trailing = Forbidden
+            }
     , Parser.backtrackable <|
       Parser.succeed (\n -> Call n [])
         |= name