Log Message:
spleen: update to 1.9.1.

Spleen 1.9.1 (2021-06-13)

- Tweak wsfont export program to account for the new block in the 6x12 version
- Mention that Haiku now uses Spleen 12x24 in the trivia section
- Fix paths to wsfont generators
- Add an 'otb' target to generate OTB files for all sizes using fonttosfnt
- Also remove generated .otb files in the 'clean' target
- Generate .dfont files again in release tarballs
- Generate OTB versions in release tarballs
- Also remove generated .dfont files in the 'clean' target