Properly set displaystyle and scriptlevel, and make sure the contents is enclosed in a single element.  Resolves both parts of issue #1152, but at the cost of possibly redundent mstyle elements.  These could be filtered out in the combineRelations() post-filter, when we can check if the displaystyle and script levels need setting.
Properly set displaystyle and scriptlevel, and make sure the contents is enclosed in a single element.  Resolves both parts of issue #1152, but at the cost of possibly redundent mstyle elements.  These could be filtered out in the combineRelations() post-filter, when we can check if the displaystyle and script levels need setting.

GerHobbelt/MathJax,mcanthony/MathJax,cheerfulstoic/MathJax,jeremykenedy/MathJax,anusornc/MathJax,thomasjm/MathJax,cben/MathJax,thomasjm/MathJax,thomasjm/MathJax,thomasjm/MathJax,nvp2211/MathJax,perseoq/MathJax,cben/MathJax,cheerfulstoic/MathJax,anusornc/MathJax,mcanthony/MathJax,anueshenxing/MathJax,wikimedia/MathJax,Edraak/MathJax,minrk/components-mathjax,GerHobbelt/MathJax,minrk/mathjax-component,jinntrance/mathjax,Edraak/MathJax,jeremykenedy/MathJax,perseoq/MathJax,ManrajGrover/MathJax,anueshenxing/MathJax,dpvc/MathJax,nvp2211/MathJax,thomasjm/MathJax,minrk/components-mathjax,ManrajGrover/MathJax,jinntrance/mathjax,minrk/mathjax-component