Lexical cast and wide characters

[brey]

It would be nice to make lexical_cast be handle to 
translate through means other than a char-width 
string.  One way to address this is follows:

template<typename Target, typename Source, typename E 
= char>
Target lexical_cast(Source arg)
{
   std::basic_stringstream<E> interpreter;
    ...

Other options, such as using traits to try to deduce E 
from the target type automatically, would be fine, 
too.  Think of the above suggestion as a starting 
point; however, it would plug what it currently a hole.

This feature request is derived from:
http://groups.yahoo.com/group/boost/message/10937