Remove use of sed and xargs from _system_info in zfs-stats
Remove mention of sed and dc from preamble
Simplify printing the horizontal bars in zfs-stats
Combine all use of backticks to a single subroutine in zfs-stats
Convert from Getopt::Std to Getopt::Long

This allows removing the compat section by using
the alternate names ability of Getopt::Long
Simplify argument processing in zfs-stats
Remove _call_all from zfs-stats
Allow running the external commands in zfs-stats on another computer

Use ssh to run the external commands if a hostname is specified
Improve usage and version argument handling to happen sooner.