Support defining SVG geometry to be used as a clipPath

[waldyrious]

The page already says

The clip-path property allows you to make complex shapes in CSS by clipping an element to a basic shape (circle, ellipse, polygon, or inset), or to an SVG source.

But only the basic shapes are supported in the live demo. The most advanced option available is the custom polygon shape editor. It would be nice to support a text box where we could add a SVG path definition to be used to clip the image. In particular, this would allow drawing curved shapes that are not circles or ellipses.