⭐️ Fix and refactorize antialiasing defaults

[wcandillon]

This PR fixes the antialiasing default for the Paint component.
The issue came up when writing the following:

<Circle color="blue" r={9} cx={9} cy={9}> 
  <Paint style="stroke" color="white" strokeWidth={2} />
</Circle>

Suddenly the edges of the circle wouldn't be anti-aliased anymore.
I took advantage of this fix, to factorize the Skia paint default settings, add an antiAlias property for paints, and fix dead anchors in the documentation.

[chrfalch]

LGTM!