Disallow transforms in simplified SVG

[JayFoxRox]

While discussing #7, we did not consider transforms.

So far, the SVG in the repository contains transforms:

• The groups are transformed to move the actual drawing towards the center.
• Some elements appear to be scaled.

We should apply these transforms and forbid them in the simplified SVG file. This means we have to explicitly check for them and bail out if any of them exist.

Applying them within the script might be tricky (we should keep our tools simple, to avoid re-implementing a full SVG editor), so ideally we should create documentation on how to export from Inkscape (or other tools) to avoid transforms (maybe https://github.com/Klowner/inkscape-applytransforms).