Add icons at missing sizes, clean up SVG metadata
Adds app icon at 64px, 96px. This should give a cleaner look in system menus like App Finder, Whisker Menu.
Update some aspect ratios to make icons more consistent at different sizes.
Remove extra content from SVGs.
Removes export path strings from SVGs, metadata which Inkscape added on export.
Note: Inkscape recently changed to save export paths as relative paths so this shouldn't be an issue in the future.