stroke-dasharray attribute on paths

I’ve started work on #134 to implement the stroke-dasharray attribute.
(docs: https://developer.mozilla.org/en-US/docs/SVG/Attribute/stroke-dasharray)

I believe everything should be set on the runner side of things, but I’m looking for some pointers on where to go in the `renderer/svg/` files to implement the receiving side of things and what the easiest way to visually and jasmine-y test it.