[boost] Yap formally accepted into Boost

Dear Boost, This message is to announce that Yap (which had been conditionally accepted [1]) is now accepted into Boost, since the conditions for acceptance have been met. The conditions for acceptance were: - Improve the documentation to satisfy Brook Milligan and myself (done) - A single macro for symmetric binary operators (done in https://github.com/tzlaine/yap/issues/22) - Get rid of external dependencies checked into repository (done) - Boost.Build (done in https://github.com/tzlaine/yap/issues/52) Congratulations Zach! Louis Dionne Review manager for Boost.Yap [1]: https://lists.boost.org/boost-announce/2018/03/0540.php