• Encode to a temporary file before renaming to the final destination to ensure atomicity and prevent partially encoded files.
• Fix auto-encode --keep function.
• Add crf-search --stdout-format json outputting newline delimited json messages,
  see stdout-format-json.md.
• Add type, crf & from_cache keys to the sample-encode --stdout-format json output.
• Improve error handling when temp dirs have insufficient permissions.