Distinguish between italic and oblique variants of a font

[jgcodes2020]

Skia supports this via the SKFontStyleSlant enum. This should be supported in RichTextKit.

[toptensoftware]

Thanks for reporting this. Are you suggesting a different style attribute to control this? Happy to add this, but currently pretty busy on other projects. Send a PR if you need it urgently and I'll consider merging it.

[jgcodes2020]

This is more of a low-priority thing. As for attributes, it could replace the existing Italic attribute, and the old property would simply either set Upright or Italic, depending on the font.