xmodmap replacement in 2020
XKB seems the way to go
- convert xmodmap to xkb: https://lists.debian.org/debian-x/2012/09/msg00274.html
- gnome 3 (shell) does not load xmodmap anymore: https://bugzilla.redhat.com/show_bug.cgi?id=873656
FIXME: howto to map some keys manually
