Changelog

• mkfs: new defaults!
• no-holes
• free-space-tree
• DUP for metadata unconditionally
• libbtrfsutil
• add missing profile defines
• libbtrfs
• minimize its impact on the other code, refactor and separate implementation where needed, cleanup afterwards, reduced header exports
• documentation
• introduce sphinx build and RST versions of manual pages, will become the new format and replace asciidoc
• fixes:
• fix warning regarding v1 space cache when only v2 (free space tree) is enabled
• fi usage: fix wrongly reported space of used or unallocated space
• fix detection of block device discard capability
• other
• lots of cleanups and refactoring
• zoned mode uses direct io for file backed images
• new and updated tests