[boost] [multiprecision] Request permision to merge to release.

I'd like to ask permission to merge the multiprecision lib to release. Note that as things stand I'm still chasing down test failures, but these are now mostly down to: * Things that work locally, but the testers haven't cycled yet. * 300s timeouts - mostly from the intel compiler :-( Aside: in an effort to reduce the number of timeouts, I've basically gutted some of the tests when the compiler is Intel, and I think I have all the build times under 20s on my Linux box, yet I'm still getting 300s timeouts on some tester machines, either those machines are seriously underpowered or I'm missing something here :-( Cheers, John.