stdlib: Add Result and Option types

Since the type checker sucks less now, we can think about maybe
adding some features to the language.

...At some point I'd like to have the type checker clean up
the index map.

stdlib/std/range.cl

@@ -1,17 +1,15 @@
 //! Iterable ranges
 
-type T = _;
-
 /// An Exclusive Range `a .. b` iterates from a to b, excluding b
-// #[lang = "range_exc", T]
-pub struct RangeExc(T, T)
+// #[lang = "range_exc"]
+pub struct RangeExc<T>(T, T)
 
 /// An Inclusive Range `a ..= b` iterates from a to b, including b
-// #[lang = "range_inc", T]
-pub struct RangeInc(T, T)
+// #[lang = "range_inc"]
+pub struct RangeInc<T>(T, T)
 
 impl RangeExc {
-    fn next(this: &RangeInc) -> T {
+    fn next<T>(this: &RangeExc) -> T {
         (*this).0
     }
 }