Support parsing half-open ranges in patterns.

Fixes #117
diff --git a/src/visit.rs b/src/visit.rs
index 8c8645d..45ad8b4 100644
--- a/src/visit.rs
+++ b/src/visit.rs
@@ -632,7 +632,7 @@
         Pat::Lit(ref expr) => {
             visitor.visit_expr(expr);
         }
-        Pat::Range(ref start, ref end) => {
+        Pat::Range(ref start, ref end, _) => {
             visitor.visit_expr(start);
             visitor.visit_expr(end);
         }