1. use BOOST_USE_FACET wrapper
2. using std::string's += operator instead of (more efficient) append for STLPORT + MSVC <= 7.0
msvc-6-stlport fails to find basic_string::append( Iter, Iter) when linking
with Iter = _STL::_DBG_iter< _STL::_Nondebug_string<char,
_STL::char_traits<char>,
_STL::allocator<char> >
might affect other MSwindows compilers.
[SVN r22236]
Samuel Krempp