Benchmark bug

Hello. You seem have a bug in the [benchmark](https://github.com/montagejs/collections/blob/592ec42395f6334c67af878983b2472cc0dd0eec/bench/sorted.js).

There's a statement
```js
return hrtime[0] * 1000 + hrtime[1] / Math.pow(2, 32);
```
which is wrong. The [process.hrtime()](http://nodejs.org/api/process.html#process_process_hrtime) returns a `[seconds, nanoseconds]` pair. Nano stands for 10**-9, not 2**-32.