Add DVD support

[kmcclive]

As a user, I want Tricycle to support reading DVD discs/folder structures so that I can transcode titles that span multiple files and retain chapter information.

[MarcoRavich]

...and, of course, would be also interesting to encode into DVD-Video format !

To (easily) achieve this, GMJCZP's "Optimal encoding with FFmpeg for DVD" script may help:

https://forum.doom9.org/showthread.php?p=1809116#post1809116

Hope that inspires !