Standardize/update current SVG images

[Randalphwa]

This PR updates all of the current SVG files with a goal of being more consistent. In particular, the following changes were made:

• Viewport removed, all document sizes are now 30x30.
• Line breaks and indentation added (means diffs in git will only reflect single line changes). Note that wxUiEditor will remove these before compression, so this has no effect on the final file size.
• All dimensions are absolute -- the transformation matrix is removed.
• Most files now have an empty outer rectangle -- this is used to ensure that the contents of the file are positioned relative to the outer border.