[ Chris Lamb ]
* Truncate jsondiff differences at 512 bytes lest they consume the entire page.
* Wrap our external call to cmp(1) with a profile (to match the internal
  profiling).
* Add a note regarding the specific ordering of the new
  all_tools_are_listed test.

[ Dimitrios Apostolou ]
* Performance improvements:
  - Improve speed of has_same_content by spawning cmp(1) less frequently.
  - Log whenever the external cmp(1) command is spawn.ed
  - Avoid invoking external diff for identical, short outputs.
* Rework handling of temporary files:
  - Clean up temporary directories as we go along, instead of at the end.
  - Delete FIFO files when the FIFO feeder's context manager exits.

[ Mattia Rizzolo ]
* Fix a number of potential crashes in --list-debian-substvars, including
  explicitly listing lipo and otool as external tools.
 - Remove redundant code and let object destructors clean up after themselves.

[ Conrad Ratschan ]
* Add a comparator for Flattened Image Trees (FIT) files, a boot image format
  used by U-Boot.