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In particular, rely on some defaults set in the emacs init module.

Unfortunately, a few sites go nuts if they don't get the path.

Also remove nixos-19.09-small.

Wasn't as much fun as I had hoped.

Instead enable them in individual configurations where they are used.

Also hard code them to cope with all websites that set either the
background or foreground color but not the other.

This includes making use of the theme-base16 to do some basic
colorizing of the Firefox newtab page.