Merge standards conformance fixes for Boost.PropertyTree
Merge documentation fixes.

* Use `doc/src/*.css` instead of `doc/html/*.css`.
* Remove wiki and people directories.
* Some documentation fixes.
* Left out `minimal.css` changes and boostbook changes because of clashes.
Merged r59734 and r61606 from trunk; fixes #3594 and #4092
Merge long-overdue PTree changes to release (boost)
Merge long-overdue PTree changes to release (libs)
Merge more PTree fixes to release (boost)
Make PTree's parser_writer_settings fields non-const, so that the struct is assignable.
Merge simple fix for non-ascii XML parsing to release. Fixes bug 4340.
Merged revisions 66498 via svnmerge from 
https://svn.boost.org/svn/boost/trunk

........
  r66498 | eric_niebler | 2010-11-11 15:28:11 -0500 (Thu, 11 Nov 2010) | 1 line
  
  add missing includes, fixes #4841
........
Merge r68990 to release just before 2.46.1, because it's a critical and low-risk fix. Sorry about not waiting for permission, but I won't have access to this computer again until after the release. So if this merge is a problem, just revert it.
Merge r68990-68993, several fixes to PTree. Fixes bug 1678. Fixes bug 4387.
Merge r68990-68993, several fixes to PTree. Fixes bug 1678. Fixes bug 4387. Forgot to commit these together with the header part.
Merge UTF-8 XML support improvements (r69622) to release. Fixes bug 5203.
Merge r70664-70666 to release. Improves INI parser and brings improvement to docs. Docs should now at least no longer contain completely incorrect examples.
Merge [72000],[72001],[72003], [74691], [75587], [75589], [75590], and [75593]
from trunk.
Fixes bug 4840.
Fixes bug 5259.
Fixes bug 5281, I think.
Fixes bug 5944.
Fixes bug 5757.
Fixes bug 5710.
Fixes bug 5307, I think.
Merge r78550 to release. Fixes an outdated test to work again. Fixes bug #6785. Fixes bug #6808.