Fix inaccurate heading id generation documentation.

All headings have ids generated, not just `h1`, `h2` and `h3`.
Update the import and include documentation.

This is a bit incoherent at the moment. It needs to be rearranged so
that there's a tutorial that introduces the concepts in a more logical
order. But I want to press on with some of the other updates.
Update version meta-data documentation.
Add explicit ids to heading documentation.
Add note about xmlbase.
Add new elements in 1.6 to the main documentation.
Fix inaccurate heading id generation documentation.

All headings have ids generated, not just `h1`, `h2` and `h3`.

git-svn-id: https://svn.boost.org/svn/boost/trunk/tools/quickbook@85402 b8fc166d-592f-0410-95f2-cb63ce0dd405
Update the import and include documentation.

This is a bit incoherent at the moment. It needs to be rearranged so
that there's a tutorial that introduces the concepts in a more logical
order. But I want to press on with some of the other updates.

git-svn-id: https://svn.boost.org/svn/boost/trunk/tools/quickbook@85403 b8fc166d-592f-0410-95f2-cb63ce0dd405
Update version meta-data documentation.

git-svn-id: https://svn.boost.org/svn/boost/trunk/tools/quickbook@85404 b8fc166d-592f-0410-95f2-cb63ce0dd405
Add explicit ids to heading documentation.

git-svn-id: https://svn.boost.org/svn/boost/trunk/tools/quickbook@85405 b8fc166d-592f-0410-95f2-cb63ce0dd405
Add note about xmlbase.

git-svn-id: https://svn.boost.org/svn/boost/trunk/tools/quickbook@85406 b8fc166d-592f-0410-95f2-cb63ce0dd405
Add new elements in 1.6 to the main documentation.

git-svn-id: https://svn.boost.org/svn/boost/trunk/tools/quickbook@85407 b8fc166d-592f-0410-95f2-cb63ce0dd405
Merge branches 'feature/document-1_6' and 'trunk'