Log Message:
spleen: update to 1.7.1.

Spleen 1.7.1 (2020-06-21)

- Add some Powerline characters (arrows symbols and padlock) (5x8 version)
- Fix duplicate character names for Powerline symbols
- Uppercase ISO in the FONT property so fonts can be processed through
  ucs2any(1)
- Add "Black Diamond" and "Lozenge" characters for all sizes
- Add "Black Heart Suit" and "Black Diamond Suit" characters \ 
for all sizes
- Remove strain pixel on the '5' digit (5x8 version)
- Improve the Esszet character (8x16, 12x24, 16x32, and 32x64 versions)