* Refactor \kern, proper \mkern support, add \hskip
* Move \kern, \mkern into functions directory
* Add \hskip, \mskip support (but without supporting plus/minus)
* Properly separate \kern, \hskip from \mkern, \mskip.
(The former work in both modes, and don't support mu units.
The latter work only in math mode and only support mu units.)
* Render \kern etc. using MathML <mspace>
* Implement \TeX macro
* Implement \LaTeX
* New KaTeX logo \katex
* Rename hskip.js -> kern.js
* Tweak katex \kern to 0.16em
* \katex kern -.17em
* Compute A raise height in \LaTeX and \katex
* Switch mu unit errors to warnings
* LaTeX screenshot test
* Replace \KaTeX with macro definition
* Update screenshots with \KaTeX in them
* Fix font selection for \*TeX macros
