v6.10.1

• mkfs: rework --rootdir traversal, skip hardlinks and create new inodes
  instead, also warn about them, this did not work as expected and will be
  fixed in the future
• receive: search in older trees for UUIDs when detecting clone sources
• libbtrfsutil: bindings available at https://pypi.org/project/btrfsutil
• libbtrfs:
  • patchlevel version update 0.1.4
  • cleanup in headers, removed unused definitions, no functional changes
  • don't ship list.h and rbtree.h
• other:
  • documentation updates