[boost] Noexcept improvements

Subject: [boost] Noexcept improvements
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2017-06-25 00:54:45

I've completed a second iteration on Noexcept, incorporating valuable
feedback from the previous discussions here, and I'd like to thank everyone
who participated.

https://zajo.github.io/boost-noexcept/

The new result<T> type has a hard value-or-error invariant and can be used
to transport errors between threads or to temporarily postpone the
consumption of function results, e.g. by storing result<T> objects into a
queue (of course, as before, users do not need result<T> just to report a
failure from a function.)

There is also a new macro, BOOST_NOEXCEPT_CHECK, which makes writing
error-neutral functions easier and improves error checking in general.

The documentation is also much more complete, including better examples and
a new section on programming techniques.