Add season and episode_or_date template substitutions

[kankaristo]

Added 2 new template substitutions:

• season_dir: Adds e.g. Season 04/ to the title, so that episodes can be put into directories. If the video does not have a season number, this results in an empty string.
• episode_or_date: This is the same as episode if the video has that available, or otherwise the same as date.

[kankaristo]

About "Season 01" vs "S01": the format "Season 01" is the most common for directory names (at least as far as I've seen), and e.g. Jellyfin requires that directory naming structure (with no way to configure it that I'm aware of).

And even "S01" isn't really "language-neutral". :P In Finnish it should really be "K01" (which is what Yle Areena uses, although without the zero-padding).

I could add some way to configure the prefix? The default could be "S", or maybe an empty string, so that you could get a "plain" season number with ${season}.

Any thoughts on how the configuration should be done (or if it's even a good idea)?

• A simple option would be a parameter, e.g. --season-prefix="Season "
• Or it could even be part of the template parameter, e.g. ${season=Season }
  • Or if in the future some templates could use multiple parameters, something like ${season:prefix=Season ,suffix=...} (but maybe that's feature-creep)

Or instead of configuring the prefix, it could be a template like Season {}, where the season number would be inserted. But then you have templates within templates, and if {} is missing, that's an error, etc., so maybe a simple prefix is better.

---

The other things sound like good changes, I'll work on those soon (probably next weekend).

[aajanki]

After thinking a bit more, let's just keep it as "Season 01" after all. All the other options would increase the complexity too much to justify it.

[kankaristo]

Made the changes discussed above. Now ${season}/xyz works identically to the earlier ${season_dir}xyz. Also rebased from master.