stdout carries one JSON object per line: stage, step, progress (done, total,
unit, est, note, frac, eta, elapsed; null while unknown), stage_end and say,
which carries every message, errors and a failed step's log tail included.
A count change goes out at most every 0.5 s, any other change at once; the
ticker now runs in json mode too and sends a count that was held back, so a
stage whose count moves rarely (the rewrite) no longer shows a stale count
until it ends. json mode never prompts; close() stops the ticker by an event
of its own and keeps the mode, so a second build in one Spyder session gets
its redraws again.
dm/tools/tests/test_nsp_progress.py covers the events, the held-back count,
the failed step's tail, the CLI error and the bar / lines / off output,
with no game files, keys or Xcode.
Co-authored-by: nocmt <nocmtone@gmail.com>
