svg parsing

[Swaagie]

referencing #75 as some basic svg shapes were already added as inline, but the list is rather incomplete. Inline svg is probably going to be a lot more common with increasing browser support. At least polyline and polygon are missing, but there might be more. As @fb55 mentioned there are several other issues with changing the inline list, perhaps we can discuss this issue here and come to a more complete fix.

[Swaagie]

Likewise for elements that are part of an filter, like feGaussianBlur or feOffset. Fact is a lot of elements can be sparse or contain child elements, explicitly closing elements atm is the only solution to making sure everything is parsed correctly.

[fb55]

In the last days, I spent several hours beginning to update this module to fully support HTML5. As far as I can tell right now, the whole transition needs at least two weeks of work, which I can't afford to spend right now.

For now, this module is only an approximation of the HTML spec. I'm willing to accept pull requests adding more void elements, but I'm aware there will always be unsupported cases.

[fb55]

Please refer to inikulin/parse5 if you need a spec-compliant parser.