Make forEach have the same interface as Array.prototype.forEach

[doug65536]

I have extended forEach to have the same behavior as the "real" Array.prototype.forEach.

• The real one passes the collection as an argument as the third parameter to the callback, useful for avoiding unnecessary closure to get the collection.
• The real one accepts a second parameter, used as the 'this' value in the callback. Also useful for avoiding unnecessary closure, and avoids having to setup var self = this.

This is almost a completely non-breaking change. The only tiny difference is, the callback is called with one additional argument. Callers should be expecting that argument in a forEach callback, that looks and acts just like Array#forEach, anyway.

The test is pretty exhaustive as well.