Center large ops, and add preliminary italic correction support.
Center large ops, and add preliminary italic correction support.

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