Log Message:
pngcrush: updated to 1.8.13

Version 1.8.13 (built with libpng-1.6.32 and zlib-1.2.11)
  Add "exit(0)" after processing "-version" argument, to avoid
    displaying the Usage information
  Fix problem with MacOS prior to Sierra; it uses CLOCK_MONOTONIC
    for some other purpose

Version 1.8.12 (built with libpng-1.6.31 and zlib-1.2.11)
  Added POWERPC-VSX support.
  Report whether using optimizations.
  Added filter_method 6 (same as filter 5 with -speed).
  Added "methods" 149-176 (that use filter_method 6).
  Changed default verbosity from 1 (normal) to 0 (quiet). Use "-v" to get
    the previous default behavior and "-v -v" to get the previous \ 
"verbose"
    behavior. The "-s" (silent) and "-q" (quiet) options \ 
behave as before.