treewide: vectorise iconography

treewide: vectorise iconography

Clear, crisp, resolution independent vector graphics replace the trusty
microscopic PNG. Some minor CSS changes were needed to constrain images
in some locations to make sure they don't consume too much space.

Iconography taken from Mate desktop theme with minor adjustments:

https://github.com/mate-desktop/mate-icon-theme/

Signed-off-by: Paul Donald <[email protected]>
(cherry picked from commit ae5d91da903b6f1d3086d6082ca622231e34f555)

treewide: vectorise iconography

follow-up to ae5d91da903b6f1d3086d6082ca622231e34f555

Signed-off-by: Paul Donald <[email protected]>
(cherry picked from commit 85fde70cd212177c83456063f781c72589565c4c)

treewide: vectorise iconography

follow-up to ae5d91da903b6f1d3086d6082ca622231e34f555

Signed-off-by: Paul Donald <[email protected]>
(cherry picked from commit fa6ca8a618f835bb890ba3c7d8adae631ca17321)

treewide: vectorise iconography

follow-up to ae5d91da903b6f1d3086d6082ca622231e34f555

Signed-off-by: Paul Donald <[email protected]>
(cherry picked from commit 1e3ebebad9bea734316b415ff0599cbc0deb8a39)

treewide: vectorise iconography

follow-up to ae5d91da903b6f1d3086d6082ca622231e34f555

tweaks to more closely resemble the old png iconography

Signed-off-by: Paul Donald <[email protected]>
(cherry picked from commit 22bcf11db7cb4292b87cfb69bb3e2759297068ca)

treewide: vectorise iconography

follow-up to ae5d91da903b6f1d3086d6082ca622231e34f555

tweaks to more closely resemble the old png iconography

Signed-off-by: Paul Donald <[email protected]>
(cherry picked from commit 750aa9e25b3fbdca2ad606413c214640bebf7a73)