doxygen-awesome-css
* add doxygen-theme-css submodule * enable theme and disable not needed code references * hide nav sync button * css and cleanup * Move comments to dedicated README to not fail config check
* readd properties * use newer doxygen version + print config update diff * readd config options * fix config * revert cache change * GITHUB md * graphviz version * Add doxygen output to .gitignore