Add BOX_CHARS constant.

This isn't used for anything yet, but will eventually be used to render
horizontal bar-graphs and time-lines.
Refactor main into various sub-functions.
Clean up ParseArgs function.

Make help text consistent. Also move function closer to main().
Display "Writing to" message just before writing.
Add --scan flag.

Currently this flag just pprints the scan.
Format UserError message consistent with argparse.
Display first line of title info in scan.

Per-title, display size and FPS information.

Also improve temporarary pprint output.
Add chapter info to --scan output.
Add audio track info to --scan output.
Add TODO comment for duration bars.
Adjust formatting of --scan output.
Clean up audio track scanning.
Add subtitles to --scan.
Remove pprint junk from --scan.
Move chapter display to end of each title's scan.
Render duration bars for chapters.
Made bar lengths indicate title length.

On a disk with multiple titles, the bars are sized realtive to the
length of longest title. This makes it easier to notice short titles
(often an indication of logo "bumps" or movie trailers).

Also, the chapter's section of the bar will now always be at least one
unit long, so that the position of very short chapters is apparent.
Fix bug when splitting title with only one chapter.
Fix up docstring.

- Add a bunch of examples.
- Move it up where it's supposed to be (above the imports).
Remove unused junk