[ImgBot] Optimize images

*Total -- 282.02kb -> 266.68kb (5.44%)

/docs/images/iviewer/iviewer.zoom_zero.png -- 1.07kb -> 0.34kb (68.01%)
/docs/images/iviewer/iviewer.zoom_fit.png -- 1.22kb -> 0.46kb (61.98%)
/docs/images/iviewer/iviewer.zoom_in.png -- 1.39kb -> 0.62kb (55.49%)
/docs/images/iviewer/iviewer.zoom_out.png -- 1.38kb -> 0.62kb (55.44%)
/docs/images/custom-icons.svg -- 5.45kb -> 3.53kb (35.22%)
/docs/images/icon-class.svg -- 4.25kb -> 3.52kb (17.34%)
/docs/images/icon-trait.svg -- 4.20kb -> 3.53kb (15.97%)
/docs/images/icon-interface.svg -- 4.20kb -> 3.53kb (15.97%)
/docs/css/phpdocumentor-clean-icons/fonts/phpdocumentor-clean-icons.dev.svg -- 3.71kb -> 3.38kb (8.98%)
/docs/css/phpdocumentor-clean-icons/fonts/phpdocumentor-clean-icons.svg -- 3.63kb -> 3.32kb (8.6%)
/docs/font/fontawesome-webfont.svg -- 251.52kb -> 243.84kb (3.05%)

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Author: ImgBotApp