[boost] [config] Visual Studio 2015 Preview CTP 5 FWIW

Subject: [boost] [config] Visual Studio 2015 Preview CTP 5 FWIW
From: Beman Dawes (bdawes_at_[hidden])
Date: 2015-02-03 09:54:16

VC++ in the 2015 CTP 5 is reporting version 19.00.22512, so needs to
be bumped in compiler/visualc.hpp.

C++14 digit separators and C++11 universal character names in literals
are supposed to be implemented, but I haven't tested them. It would
also be interesting if some of bugs in recently added C++11/14
features have been fixed.

--Beman