sstream: rename _C4_DEFINE_SCALAR_IO_OPERATOR to _C4_DEFINE_CHEVRON_IO_OPERATORS
sstream: rename _C4_DEFINE_SCALAR_IO_OPERATOR to _C4_DEFINE_CHEVRON_IO_OPERATORS

biojppm/c4stl,biojppm/c4stl,biojppm/c4stl,biojppm/c4stl,biojppm/c4stl,biojppm/c4stl