SVG Lint test

[Carlgo11]

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I've developed a SVG lint test to check for syntax errors and minification possibilities but would like feedback on if it's something that would be desirable to use or not.

While keeping in mind the barrier to entry for new contributors I wanted some way of automate testing of SVG files and provide feedback on ways to enhance the files. I've therefore designed the script to fail on errors which would cause the graphic not to be displayed properly on the website whilst providing messages (warnings) on things which could hint at the file not being very optimized. My idea is for the errors to have to be fixed before a PR can be merged but any warnings to be treated as debug/info messages for the PR author and maintainers.