Transfer svg presentation attributes to a wrapping g element

[tomasklaen]

#107 became too annoying to deal with manually, so here's a PR.

If a style or any other presentation attributes are detected on a main <svg> element, the content of a symbol will be wrapped in <g> and those attributes transferred to it.

List of presentation attributes taken from: https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/Presentation

[w0rm]

Sorry for spamming you with notifications. I was thinking to use Set instead of Array for presentationAttributes, but in the end I came up with an idea to loop through presentationAttributes and deleted my other comments.

And thanks again for taking time to implement this feature.

[w0rm]

@tomasklaen thanks, will release shortly. I will make it a major version bump because folks could be relying on the implicit attribute cleanup.

[tomasklaen]

Yeah that's wise. The new behavior will definitely cause some icons to now have hardcoded colors, since previously all fill attributes on svg were being dropped.