top level closures should work; transf is not a pass anymore; next steps for first class iterator support

tests/run/tunittests.nim

@@ -1,3 +1 @@
-import utemplates
-
-# uclosures
+import utemplates, uclosures

tests/run/uclosures.nim

@@ -4,7 +4,8 @@ test "loop variables are captured by copy":
   var funcs: seq[proc (): int {.closure.}] = @[]
   
   for i in 0..10:
-    funcs.add do -> int: return i * i
+    let ii = i
+    funcs.add do -> int: return ii * ii
 
   check funcs[0]() == 0
   check funcs[3]() == 9