[PATCH 6/6] vt: support bright backgrounds for \e[48m if unblinking

This improves schemes used by fancy new programs. For example, it lets bright powerline segments match, and fixes images shown by catimg being striped to the point of unreadability. Handling of 8-color backgrounds uses stripped 16-color value instead of a dedicated formula; this works worse for

[PATCH 6/6] vt: support bright backgrounds for \e[48m if unblinking

This improves schemes used by fancy new programs. For example, it lets bright powerline segments match, and fixes images shown by catimg being striped to the point of unreadability. Handling of 8-color backgrounds uses stripped 16-color value instead of a dedicated formula; this works worse for