Add trainer sprites

[mileswwatkins]

Include animated trainer sprites.

Namespacing to pkmn-trainer-… is probably too long. trainer-…? pkmn-trnr-?

Also, how can we programmatically limit the trainers used, to just those from one game, or maybe just leaders/E4, to avoid overburdening a Slack?

[mileswwatkins]

This is dope, though:

[mileswwatkins]

These sprites are currently not offered by the PokeAPI, AFAICT. Bummer, would have to scrape from a different, less structured source.

[mileswwatkins]

Possible sources to scrape from:

• https://archives.bulbagarden.net/w/index.php?title=Category:Generation_V_Trainer_sprites
• https://pokemon.gamepedia.com/Pok%C3%A9mon_World_Tournament
• https://pokemon.gamepedia.com/Gym_Leader
• https://pokemon.gamepedia.com/Elite_Four

Probably best to limit the scope to named characters like gym leaders, rivals, and the Elite Four?

Another issue is that some of these characters/posts change over time (eg, Koga departs his gym and leaves it to his sister Janine, or the Elite Four composition changes), and therefore there are not animated sprites available for all of these characters. Not want to be a stupid genwunner, but maybe focusing on only Kanto and Johto personalities is a good start?