Use raw_convert instead of boost::lexical_cast as it seems

Use raw_convert instead of boost::lexical_cast as it seems
that lexical_cast will sometimes use a thousands separator
(i.e. it will convert 1234 to a string 1,234).  It appears
not to be possible safely to turn this off (you have to set
the global locale).  Instead, raw_convert uses a stringstream
which you can imbue() with std::locale::classic() to turn off
the locale-specific behaviour.