Changelog

• check:
• check items in tree-log
• detect invalid file extent items for symlinks
• properly detect inode cache and suggest removal by 'clear-ino-cache'
• convert: fix symlink length checks
• fi show: remove stray newline at the end of the output
• fixes:
• open devices in write-exclusive mode in most commands, prevent concurrent mount by other programs
• rescue clear-ino-cache: fix subvolume iteration that can fail in some cases
• map-logical: fix first extent searching condition
• fi resize: warn if new size is below 256M
• tree-checker:
• slightly stricter file type validation
• verify device extent items
• other:
• documentation updates
• ship btrfs-ioctl manual page (incomplete)