Apple Swift support

Hello, I've implemented initial support for Swift language. Many things are supported at this moment. I will continue development further when I'll have more time. Please consider this pull request. Thanks.
Here was my first attempt at the more general form of this regex: 

``` ruby
id = /(?:(?!\p{M})\p{Alpha}|[^\u0000-\uFFFF\p{Co}])(?:\p{Alnum}|[^\u0000-\uFFFF\p{Co}])/
```

The `\u0000-\uFFFF` part is an attempt to exclude the Basic Multilingual Plane, I'm not sure if that works.