PyProxy methods for iterators / iterables / generators

[hoodmane]

A PyProxy of an iterable Python object is now an iterable Javascript object,
a PyProxy of a Python iterator is now an Javascript iterator,
a PyProxy of a Python generator is now a Javascript generator.

[rth]

Thanks @hoodmane ! This sounds great. Sorry not much review bandwidth at the moment, but all your suggested improvement are very much appreciated :) I'll try to have a look later in the week or next week. At the moment mostly focusing on #1102 as it's blocking a number long standing of issues.

[phorward]

Hello @hoodmane,
great, this is just another fine pull request, and as @rth said your suggestions are very much appreciated here!
The hiwire.pop_value() replacement is also another good thing coming in with this.
I hope to contribute some more reviewing bandwidth during the next days.
On my first view all looks fine on this, maybe Roman has a comment therefore I first wait at the moment.

[hoodmane]

Thanks for the review @phorward. I really appreciate all the hard work you guys put into maintaining this project. I have faith you'll get to reviewing my PRs eventually =)

[rth]

This is nice! Please add a changelog entry.

Thanks @hoodmane and @phorward !