auto merge of #5476 : thestinger/rust/bench, r=graydon

The old string benchmarks weren't very useful because the strings weren't long enough, so I just threw those out for now. I left out benchmarks of `oldmap` because it's clear that it's 30-40% slower and it doesn't implement the `Map` trait.

This also cleanly divides up `insert`, `search` and `remove`.

Author: bors

src/libcore/trie.rs

@@ -136,15 +136,13 @@ impl<T> Map<uint, T> for TrieMap<T> {
     }
 }
 
-impl<T> TrieMap<T> {
+pub impl<T> TrieMap<T> {
     /// Create an empty TrieMap
     #[inline(always)]
     static pure fn new() -> TrieMap<T> {
         TrieMap{root: TrieNode::new(), length: 0}
     }
-}
 
-impl<T> TrieMap<T> {
     /// Visit all keys in reverse order
     #[inline(always)]
     pure fn each_key_reverse(&self, f: &fn(&uint) -> bool) {