Support xcolor-style RGB \color and \textcolor

I'm using pandoc to generate both HTML+KaTeX and LaTeX form the same source.
This is a problem since KaTeX treats colors differently.

This is magenta in LaTeX + xcolor:

\color[RGB]{255,0,255}
\textcolor[RGB]{255,0,255}

This is magenta in KaTeX:

\color{#FF00FF}
\textcolor{#FF00FF}

Is it possible to add support for the shown LaTeX syntax in KaTeX?
This may sidestep the need for #750