Wrap latex-environments in \[\]

[jody-frankowski]

These are the delimiters Mathjax uses for display equations.
I'm not sure why this isn't already done. This should be an essentially free upgrade.
org-mode example for test:

\begin{align}
\frac{cx + x^2}{ca^2 + ax^2} &= \frac{x(c + x)}{a^2(c + x)} \\
&= \frac{x}{a^2}
\end{align}

[orgtre]

This was fixed in the develop branch at latest here and is not an issue in orgtre/anki-editor as far as I can see.