Tangobos += existence

[Davidl]

great work , i would test it as soon as i have some time

> Tangobos is a compatibility layer to allow most Phobos code to compile  
> of Tango. I've committed the first real revision of tangobos at  
> http://www.dsource.org/projects/tangobos/ . I've only tested it on  
> GDC+Posix, which is why this isn't a real release, but it ought to work  
> on other systems. It won't, but it should :)
>
>   - Gregor Richards