[boost] [yap] Re-announcing Yap

I posted 2-3 months ago about Yap, an expression template library I've written that I intend to propose for Boost. This is just a reminder that the library exists, and where to find it. I'm giving a talk about it at C++Now 2017, and some time after that I intend to submit it to the queue. Louis Dionne has offered to serve as review manager when the time comes. You can find the main repo on GitHub: https://github.com/tzlaine/yap And online docs are here: https://tzlaine.github.io/yap Zach