Use delimitershortfall and delimiterfactor for stretching vertical delimiters.  Resolves issue #829.
Use delimitershortfall and delimiterfactor for stretching vertical delimiters.  Resolves issue #829.

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