[Patch] regex_iterator and regex_token_iterator implementation

[Paolo Carlini]

Hi,

>Should I change them all to "_M_" or "__" format, and why?

Definitely. For the usual reason that if somebody in user code has a macro with the same name before including the header the code is busted. Of course _M_ or _S_ (vs _uppercase) is our specific convention for data members and statistics, but anyway *all* the names of implementation details must be uglified in a conforming implementation, no exceptions.

Paolo