Process command-line (CLI) options, arguments

        1) getopts, builtin, bash, ksh, zsh
           http://stackoverflow.com/questions/402377/using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options
           Also, search for option processing, including:
           http://mywiki.wooledge.org/ComplexOptionParsing

        2) perl: many, including libgetopt-euclid-perl, which
           creates man page, help automatically

        3) getopt, enhanced getopts, part of the util-linux, allows GNU "--"
           Examples: /usr/share/doc/util-linux/examples, 2016.03.27

        4) argp.sh, wrapper for getopt, creates man and help (text, XML), etc.
           Allows mixed options and arguments.
           Compiled argp.c -> argp for faster execution.
           https://sourceforge.net/projects/argpsh/, 2016.03.27

        5) shflags, wrapper for getopt, creates help, allow mixed options
           and arguments
           https://github.com/kward/shflags, 2016.08.01

        6) ksh getopts, enhanced, process GNU "--", creates man, help, etc.
           Examples: Learning the Korn Shell, O'Reilly, 2nd, p 380ff

        7) zsh zparseopts
           man zshmodules, part of zshutil

        8) getopts_long.sh, a getopts that supports long options à la GNU for POSIX
           shells 
           http://stchaz.free.fr/getopts_long.sh

        9) Suggested option names:
           http://www.shelldorado.com/goodcoding/cmdargs.html#flagnames