This adds a full table of contents for the C++14 and C++17 standards,
with status for each part.
For C++14 the list of proposals is removed, as it adds little value now
that everything is supported. For C++17 the table of proposals is
retained, because it documents he feature test macros for the features.
* doc/Makefile.am (xml_sources_manual): Add missing XML files.
* doc/Makefile.in: Regenerate.
* doc/xml/manual/status_cxx1998.xml: Refer to "this section" instead
of "this page".
* doc/xml/manual/status_cxx2011.xml: Formatting and other corrections
to the C++11 status table.
* doc/xml/manual/status_cxx2014.xml: Replace list of C++14 feature
proposals with table matching contents of the C++14 standard.
* doc/xml/manual/status_cxx2017.xml: Add table matching contents of
the C++17 standard.
* doc/html/*: Regenerate.
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