Add a way to select / deselect whole generations in settings

[chylex]

Current behaviour (optional)

Currently you can only toggle individual Pokémon, or all Pokémon at once.

Description of the desired feature (required)

There could be a checkbox next to every "Generation <X>" label, which affects all Pokémon in that generation.

Why this feature would be valuable (optional)

Saves hands 👏

How to implement this feature (optional)

IntelliJ SDK has a ThreeStateCheckBox which would probably be the most appropriate UI element for this.

I'm happy to make a PR for this.

[Karl Goffin]

Hi @chylex, this is a great idea, feel free to raise a PR for this!

[chylex]

Forgot to link the issue in commit message, so linking here: #58

[Karl Goffin]

Done in #58, to be included in the next release (1.7.0, to be released soon)