Handle math italic with mtextFontInherit, record unkown character axis properly, and get correct scaling for unknown characters.
Handle math italic with mtextFontInherit, record unkown character axis properly, and get correct scaling for unknown characters.

jinntrance/mathjax,thomasjm/MathJax,GerHobbelt/MathJax,thomasjm/MathJax,dpvc/MathJax,thomasjm/MathJax,thomasjm/MathJax,jinntrance/mathjax,GerHobbelt/MathJax,wikimedia/MathJax,thomasjm/MathJax