Fix the OS/2 font tables to prevent clipping on windows

The OS/2 values in the generated fonts were incorrect, so this corrects them. To
do this, I added some files to the khan/MathJax-dev repo, and updated the
dockerfile to use the new repo.

Test Plan:
- View the test page with chrome and firefox on linux, chrome and safari on mac,
  and IE8 and IE9 on windows, and see that none of the characters are clipped.

Auditors: alpert

dockers/MathJaxFonts/Dockerfile

@@ -3,7 +3,8 @@ MAINTAINER xymostech <xymostech@gmail.com>
 
 # Install things
 RUN apt-get -qq update
-RUN apt-get -qqy install git dvipng default-jre default-jdk texlive wget fontforge mftrace fonttools optipng advancecomp man-db build-essential unzip zlib1g-dev || true
+RUN apt-get -qqy install git dvipng default-jre default-jdk texlive wget fontforge mftrace fonttools optipng advancecomp man-db build-essential unzip zlib1g-dev python-fontforge ruby || true
+RUN gem install ttfunk --version 1.1.1
 
 # Download yuicompressor
 RUN mkdir /usr/share/yui-compressor/
@@ -27,18 +28,8 @@ RUN unzip -d sfnt2woff woff-code-latest.zip
 RUN make -C sfnt2woff
 RUN mv sfnt2woff/sfnt2woff /usr/bin/
 
-# Add a symlink so MathJax can find the TeX fonts
-RUN ln -s /usr/share/texlive/texmf-dist /usr/share/
-
 # Download and setup MathJax-dev
-RUN git clone "https://github.com/mathjax/MathJax-dev.git"
+RUN git clone "https://github.com/khan/MathJax-dev.git"
 RUN cp MathJax-dev/default.cfg MathJax-dev/custom.cfg
 RUN make -C MathJax-dev custom.cfg.pl
 
-# Fix for a new version of ttx
-RUN sed -i "s/Space.otf/Space.ttf/" MathJax-dev/fonts/OTF/TeX/makeFF
-
-# Change the names of the generated fonts and font files to KaTeX
-RUN sed -i "s/MathJax/KaTeX/g" MathJax-dev/fonts/OTF/TeX/makeFF
-RUN sed -i "s/MathJax/KaTeX/g" MathJax-dev/fonts/OTF/TeX/Makefile
-