Added self-returning Symbol.iterator/@@iterator method to iterators

[jaawerth]

closes #37

1. Adds self-returning protocols.iterator method to created iterators
2. For consistency, wraps malformed iterators with same
3. Updates the iterator test to check for iter[protocol]() === iter

[jaawerth]

Hi @jlongster,

Have you had a chance to take a look at it, and does that look alright for a merge? I've been using my fork for the ES6 interop, but I'm trying not to forget to check in before switching back. Thanks!

[jaawerth]

Due to inactivity, I'm going to close this for now so I can create a clean fork with the fix and publish it scoped, pointing back to this one. May recreate later.

[jlongster]

@jaawerth I'm sorry! I dropped out of open source for much of 2016 but I am watching things now, but haven't gone through all the old stuff. If you reopen this I can merge it.

[jlongster]

This is my only complain: can you revert this? I think it's less readable. Everything else looks good!

[jaawerth]

For sure, I saw that line when going back over it the other day and I honestly don't know what I was thinking there 🙃

[jaawerth]

@jlongster No worries; figured it was something like that, but I wanted to use this in a new project so I figured I'd just publish a fork, but no need with you back in open sourceville - welcome back!

Since I'd foolishly created this PR from the master branch of my clone, I closed this one so I could create a new fork and use master for an updated README/package.json and such. That means I can't revert anything here, but I'll get you a new PR shortly.