Adds several new REPL utilities

Also removes some broken list library functions

lib/list.tri

@@ -65,13 +65,4 @@ any? = y (\self pred : matchList
   false
   (\h z : or? (pred h) (self pred z)))
 
-unique_ = y (\self seen : matchList
-  t
-  (\head rest : matchBool
-    (self seen rest)
-    (pair head (self (pair head seen) rest))
-    (lExist? head seen)))
-unique = \xs : unique_ t xs
-
 intersect = \xs ys : filter (\x : lExist? x ys) xs
-union     = \xs ys : unique (append xs ys)