Remove the old dark theme in favor of the "dark-clear" theme
Remove the old dark theme in favor of the "dark-clear" theme

This change makes it so that the dark theme works better by default on a
wider range of terminal color schemes. This is because we do not
explicitly set the background color, so if a terminal uses a light
background color by default this avoids e.g. getting black text on a
black background (as would have been the case with the old dark theme).
This theme also works better on terminals with dark themes when they
customize their background color, too.

aisamanra/matterhorn,matterhorn-chat/matterhorn