xilem_html: Add MathML and SVG elements/DOM interface traits (#153)

* Added all MathML elements

* xilem_html: Add all SVG elements and DOM interfaces, and an example using MathML and raw SVG

* Cargo fmt

* xilem_html: Reduce boilerplate in elements, by adding a new macro match arm

* xilem_html mathml_svg example: Remove unnecessary stuff in index.html

* xilem_html: Use `mod`s for each element namespace (html, mathml, svg)

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "crates/xilem_html/web_examples/counter",
     "crates/xilem_html/web_examples/counter_custom_element",
     "crates/xilem_html/web_examples/todomvc",
+    "crates/xilem_html/web_examples/mathml_svg",
     "crates/xilem_svg",
     "crates/xilem_svg/web_examples/svgtoy",
 ]

crates/xilem_html/Cargo.toml

@@ -37,6 +37,71 @@ features = [
     "Node",
     "NodeList",
     "SvgElement",
+    "SvgaElement",
+    "SvgAnimateElement",
+    "SvgAnimateMotionElement",
+    "SvgAnimateTransformElement",
+    "SvgCircleElement",
+    "SvgClipPathElement",
+    "SvgDefsElement",
+    "SvgDescElement",
+    "SvgEllipseElement",
+    "SvgfeBlendElement",
+    "SvgfeColorMatrixElement",
+    "SvgfeComponentTransferElement",
+    "SvgfeCompositeElement",
+    "SvgfeConvolveMatrixElement",
+    "SvgfeDiffuseLightingElement",
+    "SvgfeDisplacementMapElement",
+    "SvgfeDistantLightElement",
+    "SvgfeDropShadowElement",
+    "SvgfeFloodElement",
+    "SvgfeFuncAElement",
+    "SvgfeFuncBElement",
+    "SvgfeFuncGElement",
+    "SvgfeFuncRElement",
+    "SvgfeGaussianBlurElement",
+    "SvgfeImageElement",
+    "SvgfeMergeElement",
+    "SvgfeMergeNodeElement",
+    "SvgfeMorphologyElement",
+    "SvgfeOffsetElement",
+    "SvgfePointLightElement",
+    "SvgfeSpecularLightingElement",
+    "SvgfeSpotLightElement",
+    "SvgfeTileElement",
+    "SvgfeTurbulenceElement",
+    "SvgFilterElement",
+    "SvgForeignObjectElement",
+    "SvggElement",
+    # "SvgHatchElement",
+    # "SvgHatchpathElement",
+    "SvgImageElement",
+    "SvgLineElement",
+    "SvgLinearGradientElement",
+    "SvgMarkerElement",
+    "SvgMaskElement",
+    "SvgMetadataElement",
+    "SvgmPathElement",
+    "SvgPathElement",
+    "SvgPatternElement",
+    "SvgPolygonElement",
+    "SvgPolylineElement",
+    "SvgRadialGradientElement",
+    "SvgRectElement",
+    "SvgScriptElement",
+    "SvgSetElement",
+    "SvgStopElement",
+    "SvgStyleElement",
+    "SvgsvgElement",
+    "SvgSwitchElement",
+    "SvgSymbolElement",
+    "SvgTextElement",
+    "SvgTextPathElement",
+    "SvgTitleElement",
+    "SvgtSpanElement",
+    "SvgUseElement",
+    "SvgViewElement",
     "Text",
     "Window",
     "FocusEvent",