Here is a patch. It removes quite a few LOC.

> I think option 3 is better. Is there any use case left for :use-xcolor?

Every other previewer has :use-xcolor t. I assume it's safe to simply
ignore :use-xcolor if it's there except that some user has configured
a converter that for some reason requires the color command line args,
in which case he will get an error (because of the color placeholders
left untouched in the command line template).

> Thank you for taking care of this.

Well, thank you for taking care of everything else ;)

Best regards
--
Carlos