Log Message:
Update to 1.56b:

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Version 1.56b:
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  - Renamed related_work.txt to historical_notes.txt.

  - Made minor edits to the ASAN doc.

  - Added docs/sister_projects.txt with a list of inspired or closely
    related utilities.

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Version 1.55b:
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  - Fixed a glitch with afl-showmap opening /dev/null with O_RDONLY when
    running in quiet mode. Spotted by Tyler Nighswander.

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Version 1.54b:
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  - Added another postprocessor example for PNG.

  - Made a cosmetic fix to realloc() handling in experimental/post_library/,
    suggested by Jakub Wilk.

  - Improved -ldl handling. Suggested by Jakub Wilk.

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Version 1.53b:
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  - Fixed an -l ordering issue that is apparently still a problem on Ubuntu.
    Spotted by William Robinet.

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Version 1.52b:
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  - Added support for file format postprocessors. Requested by Ben Nagy. This
    feature is intentionally buried, since it's fairly easy to misuse and
    useful only in some scenarios. See experimental/post_library/.

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Version 1.51b:
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  - Made it possible to properly override LD_BIND_NOW after one very unusual
    report of trouble.

  - Cleaned up typos, thanks to Jakub Wilk.

  - Fixed a bug in AFL_DUMB_FORKSRV.