Various codegen fixes

sample-programs/loop.crf

@@ -0,0 +1,18 @@
+main = for 0 1000
+
+for x n = case n of 
+    0 => 0
+    n => for (revRange 1000) (n + minusOne)
+
+data List (a) where
+    Nil : List (a)
+    Cons : a -> List (a) -> List (a)
+
+-- create a list of x to 0
+revRange x = case x of 
+    0 => Cons x Nil
+    x => Cons x (revRange (x + minusOne))
+
+-- represents minus one :)
+minusOne : Int ;
+minusOne = 9223372036854775807 + 9223372036854775807 + 1;