Adding @defgroup and @ingroup doxygen tags into all headers
in the common folder that contain doxygen blocks.
This improves the structure, readability, and findability
of information in the resulting output.
This commit targets purely structure and does not deal with
the content of the currently existing doxygen documentation.
This tries to make our code a bit more compliant with our code formatting
conventions. For future use, this is the command I used:
git ls-files "*.cpp" "*.h" | xargs sed -i -e 's/[ \t]*$//'
