Adds support for property overrides (WIP)

Adds support for property overrides (-o property=value), property
excludes (-x property) and dataset limits (-l <volume|filesystem>)
to zfs receive.

Both -o and -x options mirror the functionality already available
in Oracle's ZFS implementation which is also mentioned in the
upstream feature request #2745:

The -l option allows receive to be limited to specific datasets within
the stream effectively allowing partial restores from a multi dataset
stream.

References:
  https://www.illumos.org/issues/2745

Ported-by: Milan-Benes
Issue #1350

NOTES: Man page updates missing and must be added, see patch:
http://blog.multiplay.co.uk/dropzone/freebsd/zfs-recv-properties.patch
Explanation on merges etc.