Adds Underscore.js and Lodash.js to the benchmarks

Unfortunately, it looks like lodash consistently outperforms fast in the `.forEach()` test, and occasionally in the Array tests with `1000` items.

This *could* just be a matter of using a while loop instead of a for loop, at least on the occasional wins for lodash.

Lodash's `forEach` also uses a `while` loop, but on top of that, they don't set the context each time using `call`. They'll call the function using traditional notation unless you specify a context. I'm not sure if `fn.call()` is slower than `fn()`, but it's a possible reason for lodash's success.
Lo-Dash opts to slow down the initial `_.bind` call to store metadata on the function. However the produced function is optimized. The metadata allows composition `_.bind`, `_.partial`, `_.partialRight`, `_.curry`, `_.curryRight`, `_.wrap` to never wrap the function more than 1 level /@megawac