Changelog (v1.36.0...v1.37.0)

• bug #584 Drop SPL "\0" special key from deepclone_hydrate() (@nicolas-grekas)
• bug #577 Cap IS_LONG objectMeta count at 1M (@nicolas-grekas)
• feature #576 Drop scoped mode — mangled-only is now the only shape (@nicolas-grekas)
• feature #574 Add DEEPCLONE_HYDRATE_PRESERVE_REFS flag + hot-path perf (@nicolas-grekas)