Execution should not continue upon failure of certain zfs commands. In
particular, cleanup/rotation of the oldest snapshots will no longer
occur upon a failure to send/receive.
Change zfs receive command to use -e (was -d).
Allow greater control of dest placement. srcpool/a/really/long/path
should not force me to deal with destpool/backupdest/a/really/long/path.
* supports either local or remote usage
* always uses sudo
* getopts for a few settings
* keeps its own snapshots for send/recv purposes, independent of others
