Syntax: <include filename="file.xml" />

The fmt library happily accepts std::string without
any conversions.

Include spdlog via BaseLib/Logging.h, which
provides macro replacements for
ERR/DBUG/WARN/INFO...

Fixes multiple copyright messages in the doxygen docu.

ag '\\file' -L --ignore=ThirdParty *Lib |xargs  sed -i 's/\(.*\)\\copyright/\1\\file\n\1\\copyright/'

Clang format run on near-the-header lines.

Happy New Year