* Improve SVG Performance
This PR introduces three new classes: `svgNode`, `pathNode`, and `lineNode`. SVG data is then loaded into the domTree exclusively via instances of these classes.
`innerHTML` is banished.
* Fix lint errors
* Fix \cancel typo
* Fix sqrt height
* Adjust min-lenght
Adjust some of the extensible arrows to get a min-length that matches glyph length of the long arrows in KaTeX Main font range from Unicode 27F5 to 27FC.
The accent arrows still get min-lengths that match the arrows in the Unicode 2100 range.
* regenerate screenshots after optimizing SVG code
* update DisplayStyle screenshot for Chrome
* update OverUnderset and Smash screenshots for Chrome as well
* Remove escapes from template strings
* Pick up review comments
* Fix lint errors
* Add comments
* Improve \sqrt
Make \sqrt out of inline SVGs to ensure a perfect match at the junction between surd and viniculum.
* Tweak for kern clarity
* Fix lint error
* regenerate screenshot tests with sqrts
* Correct advance
Edit the SVG paths so that they have the correct left bearing and advance width values.
This will correct the spacing on the left side of each surd and it will also improve the placment of a root indice.
* Revise scriptstyle surds
In the `main` size, delimiters *do* scale with scriptstyle and scriptscriptstyle.
* update screenshot images containing sqrts
The combination of jspngopt and pako should eliminate possible causes for
different PNG encodings, although the core reason for #325 remains unknown.
Pako has poorer compression rates than native libz, but optimization can
counter that effect, and actually reduce the size of the screenshots.
The screenshots for LimitControls and UnsupportedCmds on Firefox used to
exhibit subpixel rendering before, for reasons unknown. The regenerated
versions don't exhibit this. See #324 for a discussion.
