Swift doc generation

[mxswd]

This would be really good for Swift. We could do something like Haddock.

I would love to have a Writer that can write to a database for each commit / tag and have a web server serve up the docs.

Filtering out everything that is not public helps people understand the APIs to libraries.

Hopefully, it is just a case of linking the right libraries together.

[jspahrsummers]

Swift documentation is officially written in rST, and assumably Apple's Headerdoc will be updated to support it. If that's the case, it already seems better than Objective-C, which required some perverse Javadoc-style syntax.