v5.6.1

Fixed

• canonicalizeStrict (and so entry hashing) no longer rejects an input that
  reaches the same object or array from two places -- one instance referenced
  twice, not two equal copies. The circular-reference check tracked every
  value ever visited rather than the current recursion path, so an ordinary
  acyclic graph -- a signed zcap whose proof carries the same @context array
  instance as the document, embedded in a log entry -- threw
  Canonicalization input contains circular references. Such an input now
  hashes as its JSON round trip does; a value that genuinely contains itself
  still throws.