Dark Theme ("Mode") for Markdown Preview. Please. Pretty please.

[PhillipRichdale]

I'd like the great Markdown All In One™ to also include a dark theme for the entire Markdown preview. After all, If I have to fiddle with an extra Markdown Preview Enhanced Extension and do config stunts to get that working it's not really "All In One" is it? nudge nudge :-)

Otherwise: Thanks for the work. Nice extension.