Pimpl withdrawn from the review schedule.
Merge branch 'master' of https://github.com/boostorg/website
Updated changes for Atomic, Core, Log, Utility

* Added a few changes to Atomic.
* Added changes for Log.
* Added a note about the new Core library.
* Added changes to Utility.
Rebuild release notes
Merge branch 'pr/21'
More updates on Optional
Rebuild
Merge branch 'pr/22'
Add think-cell shrink-wrap user.
Merge pull request #23 from pabristow/think-cell

Add think-cell shrink-wrap user.
Create section for modularization info.
Add type_index to release notes.
List all new modules.
Shuffle some text around.
Fix resolve_url for absolute urls.
Merge branch 'beta'
Update release notes for boost_1_56
Rebuild release notes
Merge branch 'pr/24'
Add Dynamic_Bitset changes for 1.56.0