Swift 2.2 and Xcode 7.3

[phatblat]

General changes to get Nimble to build on Xcode 7.3 without warnings (aside from "Embedded dylibs/frameworks only run on iOS 8 or later")

• Replace deprecated __FILE__, __LINE__ and __FUNCTION__ with #file, #line and #function, respectively
• Use new associatedtype keyword
• Fixed a couple OS X tests that were failing due to @3 not coming through as optional

Supersedes #265

⚠️ These changes require Xcode 7.3 and Swift 2.2 or better.

[briancroom]

Cool, thanks @phatblat for putting this together! (also thanks @younata for your previous work on this)

Since Xcode 7.3 is out of beta now, I think it would make sense to merge this into master, even though it contains breaking changes. Users who need to stick with earlier Swift versions can continue using the previous releases, and the next release which includes these changes can be 4.0, bumping the version major number. Does that seem right, @jeffh?

[younata]

Thanks for doing this, @briancroom. Wish I had time (this is a lie, I've had time - I've just been busy with other projects) to see this through.

[jlalvarez18]

What's the status update on this pull request?

[phatblat]

@jlalvarez18 this PR is brand-spankin' new but looks like I didn't break anything, so just a matter of the maintainers reviewing it and then buttoning up a release. 🚢

[modocache]

Breaking changes be damned, I'm merging this.

[modocache]

@phatblat Don't suppose I could trouble you to update the Nimble submodule in the Quick build...? 🙏

[phatblat]

On it

[jeffh]

@briancroom, yeah it's ok to merge into master since Swift 2.2 is out.