Region headers

Sorry for another huge pr.

Moved over to using JSON files that contain both the region and cue data for the vtt file. We can compare entire vtt files to a single JSON file now.

Updated cue2json. It can now:
* Output json data straight to console.
* Output json data to a json file with the same name as the vtt file with the option '-f'.
* Walk a directory tree and rewrite all json files it finds that have a corresponding vtt file. Dangerous, but it allowed us to move this over quickly to this new json format quickly.