[patch] std::string::operator[] extension in debug mode

[Paolo Carlini]

Jonathan Wakely wrote:

>[]
>
>The important thing is that debug mode never interferes with normal
>mode.  As long as that's true debug mode has a fair bit of freedom to
>be "creative" with the standard.
>
>Just my opinion, of course.
>  
>
I agree. Only, adding always_inline everywhere doesn't seem feasible...

Paolo.