Improve command line argument handling

- Truncate help at console width
- Add 'z' character to indicate line break in help output
- Add end-of-line truncate indicator '<>'
Finalize retty-print command-line options help

wp_options.w:
- Improve const-ness
- General: Documentation and file reorganization
- Iterate command-line option struct and display correct help to the
  user; attempt to adjust help per user terminal column width