v0.8.2

A fifth fuzzing round, run before 0.8.1 reached crates.io, found three more
cases. 0.8.1 was published on GitHub only; this release supersedes it. The
parity audit still reads 196 / 196 files identical to ExifTool 13.59.

Fixed

• CRW (Canon RAW): sibling entries pointing at the same sub-directory were
  read again at every level, so a 54 KB file grew past 2 GB of tags. A
  directory is now read once, as ExifTool's PROCESSED check does.
• PDF: an octal escape above \377 in a string overflowed a byte; the high
  bit is dropped, as the PDF specification says.

Full Changelog: v0.8.0...v0.8.2 (0.8.1 was not published to crates.io; its fixes are included)