Boost argument parser as a replacement for normal argument parsing.

• All original argument parsing is replaced by structures from boost::parse_arguments
  • This means some command-line flags will have to be changed slightly (boost uses -- instead of - as full-word command prefix)
• Removed freq-avg and time-avg flags, as they were never being used, and will not be used when we do per-timestep imaging.
• Removed unused Setters for Aartfaac2ms, as they are replaced by the new argument parsing.