Major bug fixes and overall improvements

• Fixed syntax error introduced in 1.0 thanks to @MarcelFox
• Fixed issue #36 (cron file created incorrectly).
• Added cron job deprecation warning, daemon mode should be used instead.
• Fixed many issues reported by shellcheck.
• Added IPv6 support
• Use ss instead of netstat.
• started some drafting to add blocking by port support.
• Improved ban_incoming_only
• Eliminate some command steps to improve performance.
• Removed HOST_IP since it is no longer necessary.
• Fixed improper call to grepcidr.
• Minor man page changes.
• Added ip6tables to dependencies list and removed netstat.