rewritten bash (non portable) code into standard posix

tested on dash 057
fixes
missing \n in fs list expansion, remote and local snapshot testing.
update to snapshot list to destroy prior to fall back and -R
put back parameter checking before destroy of remote snapshots (case of fallback)
Merge commit '6cef3c094c526da3778e4a29d999ba6e22cbdbe7' into zevo

Conflicts:
	src/zfs-auto-snapshot.sh