Illumos #1644, #1645, #1646, #1647, #1708

Illumos #1644, #1645, #1646, #1647, #1708

1644 add ZFS "clones" property
1645 add ZFS "written" and "written@..." properties
1646 "zfs send" should estimate size of stream
1647 "zfs destroy" should determine space reclaimed by
     destroying multiple snapshots
1708 adjust size of zpool history data

References:
  https://www.illumos.org/issues/1644
  https://www.illumos.org/issues/1645
  https://www.illumos.org/issues/1646
  https://www.illumos.org/issues/1647
  https://www.illumos.org/issues/1708

This commit modifies the user to kernel space ioctl ABI.  Extra
care should be taken when updating to ensure both the kernel
modules and utilities are updated.  This change has reordered
all of the new ioctl()s to the end of the list.  This should
help minimize this issue in the future.

Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Reviewed by: Albert Lee <trisk@opensolaris.org>
Approved by: Garrett D'Amore <garret@nexenta.com>

Ported by: Martin Matuska <martin@matuska.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #826
Closes #664