Add optional doxygen configure file.
Add optional doxygen configure file.

* /incubator-corinthia/DocFormats/doxygen-extract-all.cfg

    Extract everything, including undocumented items as per Step 3 in
    the Doxygen 'Get started' page:

    http://www.stack.nl/~dimitri/doxygen/manual/starting.html#step3

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