[boost] [release] Master branch now completely closed for the 1.70.0 release

Subject: [boost] [release] Master branch now completely closed for the 1.70.0 release
From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2019-04-04 14:24:47

The master branch is now closed for all changes except by permission for
the release.

Also, remember to add your libraries' changes to the release notes at:
    <
https://github.com/boostorg/website/blob/master/feed/history/boost_1_70_0.qbk
>

Thanks,

-- The Boost Release Team