Optimize and unify markup of SVGs and align to WikimediaUI color palette where easily applicable. Also removing three unused image files. Bug: T153043 Bug: T178867 Change-Id: Ied457ef84357374e66db9e1936ce1b754d53cfdb
This is the final step of the process described at <https://www.mediawiki.org/wiki/Separating_skins_from_core_MediaWiki>. Corresponding core change: Idfc38503. Change-Id: I84fcf7ce6385b8323544cafe6912a00f1886d20d