Add sphinx linkcode (#440)
* add linkcode extension resolving to github
* copybutton: exclude propt text from copies
* Use downloaded shared sphinxconfig
Co-authored-by: Andreas Kloeckner <inform@tiker.net>
* add linkcode extension resolving to github
* copybutton: exclude propt text from copies
* Use downloaded shared sphinxconfig
Co-authored-by: Andreas Kloeckner <inform@tiker.net>