Use `--` to separate args and URLs

[minijackson]

Hello and thanks for this tool!

I've noticed that the original ff2mpv code was using -- to separate args and urls, like this:

mpv --args -- $url

Which I think is good from a security perspective. Would you be open to adding it?

I've also seen that it always adds --no-terminal to the options (see woodruffw/ff2mpv#1)

[ryze312]

Hey thanks for the suggestion! This is certainly a good idea, will implement shortly.