unsigned array indexes work better; minor cleanups

tests/implicit/timplictderef.nim

@@ -1,9 +1,10 @@
 discard """
-  output: "2"
+  output: '''2
+88'''
 """
 
 type
-  TValue* {.pure, final.} = object of TObject
+  TValue* {.pure, final.} = object of RootObj
     a: int
   PValue = ref TValue
   PPValue = ptr PValue
@@ -16,3 +17,19 @@ var sp: PPValue = addr x
 sp.a = 2
 if sp.a == 2: echo 2  # with sp[].a the error is gone
 
+# Test the new auto-deref a little
+
+{.experimental.}
+
+proc p(x: var int; y: int) = x += y
+
+block:
+  var x: ref int
+  new(x)
+
+  x.p(44)
+
+  var indirect = p
+  x.indirect(44)
+
+  echo x[]