Updated Stark theme to support LaTeX source

LaTeX code was [not very good]() with the current Stark theme, so I updated it with very specific scopes for LaTeX.  Some of the colors could probably be adjusted some, but I found this much more appealing than all gold and white.

[old](http://puu.sh/21tdH/e38b4bec70)

[new](http://puu.sh/21wEl/c9f645d28f)