Machine-parseable progress reporting

[bdon]

• output line-oriented JSON to stderr
• Abstract away use of fprintf to stderr
• collect diagnostic information on program exit, if exit failure

[bdon]

• Need a global singleton to set JSON vs interactive terminal progress reporting
• Progress consists of a few parts:
  • input parsing, where the total # of elements and thus % progress is unknown
  • reordering (% progress)
  • tiling (% progress) so it may be difficult to derive a single % progress number