[v3] ext/type_traits.h

[Benjamin Kosnik]

> My only doubt is about uglification: are we sure we want to add the 
> non-uglified names numeric_traits and conditional_type (maybe other)?  

We don't, you're right.

> It's also a matter of consistency because generally we do uglify 
> everything else (e.g., _Value,  _Cond,  _To_unsigned_type...). 

Yep. I'm trying to improve consistency here...

> Personally, to be on the safe side, I'm trying to consistently uglify 
> all the new code as mush as possible, same policy of the library proper 
> in /ext and /tr1, that is. I was even thinking adjusting unordered_* 
> containers and be done with it...

Yeah. Good idea. Now that tr1:: can be considered part of std::, it
only makes sense to play by the rules that std:: is using.

-benjamin