Replace remaining PNG files with SVG files

[Pander]

Please replace remaining PNG files with SVG files. Note that animated PNG files should remain as is. The files that should be replaced can be found in source code are:

$ find . -name '*\.png'|grep -v '\-spinner\.png'|grep -v '\-working\.png'
./Humanity-Dark/status/16/audio-volume-low.png
./Humanity-Dark/status/16/audio-volume-medium.png
./Humanity-Dark/status/16/audio-volume-high.png
./Humanity-Dark/status/16/audio-volume-muted.png
./Humanity-Dark/status/22/audio-volume-low.png
./Humanity-Dark/status/22/audio-volume-medium.png
./Humanity-Dark/status/22/audio-volume-high.png
./Humanity-Dark/status/22/audio-volume-muted.png
./Humanity-Dark/status/24/audio-volume-low.png
./Humanity-Dark/status/24/audio-volume-medium.png
./Humanity-Dark/status/24/audio-volume-high.png
./Humanity-Dark/status/24/audio-volume-muted.png
./Humanity/apps/16/seahorse.png
./Humanity/apps/16/seahorse-preferences.png
./Humanity/apps/16/keyring-manager.png
./Humanity/apps/16/stock_keyring.png
./Humanity/apps/24/badge-small.png
./Humanity/apps/24/password.png
./Humanity/apps/24/seahorse.png
./Humanity/apps/24/seahorse-preferences.png
./Humanity/apps/24/keyring-manager.png
./Humanity/apps/24/stock_keyring.png
./Humanity/apps/32/xfce4-weather.png
./Humanity/status/16/audio-volume-low.png
./Humanity/status/16/gtk-dialog-authentication.png
./Humanity/status/16/audio-volume-medium.png
./Humanity/status/16/audio-volume-high.png
./Humanity/status/16/audio-volume-muted.png
./Humanity/status/16/dialog-password.png
./Humanity/status/22/audio-volume-low.png
./Humanity/status/22/audio-volume-medium.png
./Humanity/status/22/audio-volume-high.png
./Humanity/status/22/audio-volume-muted.png
./Humanity/status/24/audio-volume-low.png
./Humanity/status/24/gtk-dialog-authentication.png
./Humanity/status/24/audio-volume-medium.png
./Humanity/status/24/audio-volume-high.png
./Humanity/status/24/audio-volume-muted.png
./Humanity/status/24/dialog-password.png
./Humanity/emblems/16/emblem-ohno.png
./Humanity/emblems/16/emblem-cool.png
./Humanity/emblems/16/emblem-OK.png
./Humanity/emblems/22/emblem-ohno.png
./Humanity/emblems/22/emblem-cool.png
./Humanity/emblems/22/emblem-OK.png
./Humanity/emblems/24/emblem-ohno.png
./Humanity/emblems/24/emblem-cool.png
./Humanity/emblems/24/emblem-OK.png
./Humanity/emblems/32/emblem-ohno.png
./Humanity/emblems/32/emblem-cool.png
./Humanity/emblems/32/emblem-OK.png

For the files above, SVG files do exist of other (usually higher) dimensions. These can be used to create optimized SVG files to replace these specific PNG files. Note: symlinking to scalable icons of other dimensions is not allowed here.

Please incorporate a similar check in e.g. make test

Fixing this will make the humanity icon theme 100% scalable.