[boost] 1.65 closes for new libraries and breaking changes this Friday

[ The calendar says today, but I forgot to send this out, so we're pushing the deadline back two days. ] Upcoming release dates: 28-Jun: Boost 1.65.0 closed for major changes 5-Jul: Boost 1.65.0 closed for all changes, except by permission of a release manager. 8-Jul: Boost 1.65.0 closed for all changes 12-Jul: Boost 1.65.0 beta; master branch re-opened 2-Aug: Release closed for all changes, except by permission of a release manager. 5-Aug: Boost 1.65.0 closed for all changes 9-Aug: Boost 1.65.0 release -- Marshall