HiDPI support in preview images #92
Description
I would like to investigate HiDPI support in preview images so people with hi-resolution displays (or zoomed in) can see the full effect of LilyPond's typesetting before downloading.
This would involve creating two preview images, one at double the resolution, and using the srcset attribute to choose between them. XKCD does something like this:
http://xkcd.com/1769/
http://imgs.xkcd.com/comics/never_seen_star_wars.png
http://imgs.xkcd.com/comics/never_seen_star_wars_2x.png
