Consider a "hide media" setting

[piperhaywood]

If you’re on a crap internet connection, want to save on mobile bandwidth, or just don’t want to use as much energy, you might want to hide images on a website. Could we make this an option, either w/in the theme settings or exposed to the user?

[piperhaywood]

Could still display something in its place, like the alt text set in to a pattern across the image area. Can probably use Imagemagick to detect the predominant color in an image as well (but this might clash with #30)