Puckfetcher

* BUGFIXES
* Prefer user settings per-sub over cache settings per-sub (expected but not actual
behavior).

* BUGFIXES
* Write metadata (entry and sub) to cache.

* DEV
* Pull ID3v2 tags into subscription metadata if there isn't already data there.
* Pull tags into metatada on entries (and add that as a dict to the dict).

* DEV
* Several rebuilds to get builds to work again.
* Include drewtilities util library to share some stuff between projects.

* FEATURES:
* Fill in ID3v2 tags.
* Set "set_tags = true" in global config to enable.
* Please supply any/all of 'album', 'album_artist', and 'artist' in per-sub config.
* If you have a subscription where you want to overwrite the MP3 filename with the RSS
* title, set "overwrite_title" to true in the per-sub config.

* DEV
* Fix missed non-Python3.6 formatted strings instances.
* Get rid of textwrap.
* Update all dependencies to latest version, re-pin.

* BREAKING:
* Only Python 3.6+ are supported now.

* DEV:
* Use Python3.6 formatted strings and variable annotations.