The NVCC compiler fails to compile the date library due
to a compiler bug which causes it to emit an error when
directly using std::ratio_{multiply,divide} in the template
instantiations for std::duration. This PR works around the
issue by introducing custom ratio_{multiply,divide} which
delegate to the standard library templates
* For format, all a type must do is implement to_stream.
* For parse, each type X must specialize parse_manip<X,CharT,Traits>.
Each specialization must include a public typedef to itself named
type.
* Each parse_manip specialization must have a stream extraction
operator.
* This commit depends on expression-SFINAE. If this commit breaks
your build, it is likely that your compiler/version does not
support expression-SFINAE. To fix this NO_EXPRESSION_SFINAE
needs to be defined in the configuration area of date.h for
that compiler/version.
