Log Message:
spleen: update to 1.8.0.

Spleen 1.8.0 (2020-06-29)

- Add Initial 6x12 version, containing printable ASCII characters, the
  Braille Patterns Unicode block, and light Box Drawing characters
- Improve ampersand character, making it more consistent with other
  sizes (5x8 version)
- Add instructions on how to use Spleen in the NetBSD console