Merge fom trunk:
* Boost.Variant now uses traits from Boost.TypeTraits instead of its own (fixes #8296)

[SVN r83544]
System/FileSystem: merge from trunk to fix #7278.

[SVN r83550]
Merge pool image fixes for case sensitive filesystems.

[SVN r83580]
Chrono: merge from trunk 1.54.

[SVN r83624]
merge [83308] and [83392] from trunk, fixes #6926

[SVN r83633]
Thread: merge from trunk 1.54. Fix #8027,#8323,#8337.

[SVN r83660]
Merge fix for #8326, plus misc valgrind errors.
Refs #8326.

[SVN r83669]
Merge exception details in getting started guide. Fixes #8263.

[SVN r83685]
Merge adding locale to getting started guide. Fixes #8264.

[SVN r83687]
Merge from trunk:
* Fix stream related issues with libc++ and clang (fixes #7704, fixes #8267)
* Change runtime assert to compile time when converting to pointer (fixes #8267)

[SVN r83689]
Spirit: Merging from trunk

[SVN r83739]
Merged rev. 82588-83755

[SVN r83757]
Merged rev. 83038-83758

[SVN r83760]
Mrege from trunk:
* Disable UTF16 and UTF32 tests for libc++ (fixes #8369)

[SVN r83764]
merged rev. 83768

[SVN r83769]
Thread: merge from trunk 1.54: Added lambda tests, refactored future::then, added tests for future::wait...

[SVN r83811]
Chrono: merge doc to fix #8370.


[SVN r83814]
Merge revision(s) 83827 from trunk:
Small improvements to make_shared documentation.
........


[SVN r83828]
Merge revision(s) 83829 from trunk:
More small cosmetic documentation changes.
........

[SVN r83830]
Wave: merging from trunk

[SVN r83839]