Add SvgAttrs (SVG attributes) according to MDN specifications (https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute)
wip example project works
Merge https://github.com/mathieuleclaire/scalatags
- Deleted the unmaintained/untested `SvgStyles` entirely and swapped over to matthieus' more-complete `SvgAttrs`
- Implemented basic `Namespace` support, where each tag knows its own namespace URI, allowing SVG tags to render correctly on the client using `createElementNS`
- Completed `example/` project, which compiles successfully with both `JsDom` and `Text`, and draws a nice sampling of HTML and SVG tags.
tweak doccomment