x11/bosd: Update to 10.4

Add a CHANGELOG and example glyph scripts. Speed up example PNG
generation. Install 15 new PNG examples.

Changelog: https://github.com/FrauBSD/bosd/blob/10.4/CHANGELOG.md

Approved by: fuz (mentor)
Reviewed by: fuz (mentor)
Differential Revision: https://reviews.freebsd.org/D59715