add DList example

examples/dlist.rs

@@ -0,0 +1,14 @@
+#![feature(phase)]
+
+#[phase(plugin)]
+extern crate rust_clippy;
+extern crate collections;
+use collections::dlist::DList;
+
+pub fn test(foo: DList<uint>) {
+    println!("{}", foo)
+}
+
+fn main(){
+    test(DList::new());
+}