Fixed/added 'ip(6)tables' and 'update' functionality and improved organization:

   Now we explicitly handle ip(6)tables
   Totally enable or disable them, regardless if running or not

   Got CentOS en/disable automatic updates, and maybe security only updates too
   Reduced CentOS update-check code to a one-liner
   Fixed both OS's update variable to not be run until after prompt

   Revamped organization. Now takes startup flags that call functions:
      -a
         Run all steps...
      -p
         Change password...
      -t
         Enable or disable ip(6)tables...
      -u
         Check/install updates and automatic update setup...

The organization isn't super pretty yet, but most of it works