jo: update to 1.7.

2022-10-29 1.7
- FIX: fix warnings on Windows build and reimplement err{x,} functions
- FIX: fix reading of long lines from stdin and refactor slurp_file() in
  the process
- NEW: Add option -o outfile for when not run from a shell and redirect
  '>' is not an option
- FIX: fix tables in jo.md

(fcambus)