[0.4.0-gamma] Add support for 7.26

[djs55]

This PR includes support for 7.24, 7.25 and 7.26 and sets the default to 7.26.

The differences are

• lseek (for SEEK_HOLE and SEEK_DATA)
• FUSE_PARALLEL_DIROPS: allow parallel lookups and readdir
• FUSE_HANDLE_KILLPRIV: fs handles killing suid/sgid/cap on write/chown/trunc
• FUSE_POSIX_ACL: filesystem supports posix acls