Enhance KaTeX in lecture slides

[JamesNZL]

Description

I personally find it difficult to read equations in the form $x/y$, and much easier to quickly identify $\dfrac{x}{y}$ or even $\tfrac{x}{y}$.

I also find it hard to parse when regular text is displayed in the default italicised maths font, as I find it difficult to quickly identify the mathematical variables.

I intend to open a pull request with changes as described above, but I'm opening this issue in the meantime.

Examples

Current

Suggested Replacement

$$ V_\text{if} = G_\text{is}G_\text{io}I_\text{L} + V_\text{off} $$

Current

Suggested Replacement

$$ I_\text{L}[i]=\dfrac{\texttt{ADC1Value}[i]\times \tfrac{5}{1024}-V_\text{off}}{G_\text{is}G_\text{io}} $$

Current

Suggested Replacement

$$ \overline{V}_\text{AC}[i]=\tfrac{1}{2}\left(V_\text{AC}[i]+V_\text{AC}[i+1]\right) $$