Doubles support

[szymonWojdat]

I started messing around with doubles and managed to successfully play a couple of turns but before I proceed with this, I think it's important to decide in which direction do we want to go with this design-wise as there's a couple options:

1. Create DoubleBattle class that extends Battle, same with DoublesPlayers that extends Player
2. Make backwards-incompatible changes to Player and Battle classes so that they support both singles at doubles at the same time. This seems like a more elegant way but will involve more work and testing (which I'm fine with). Eg. Battle.active_pokemon will need to return an iterable of Pokemon instances rather than one instance and so on.

Please let me know what do you think @hsahovic

[hsahovic]

Hi @szymonWojdat!

Thanks for opening this issue.
That is a hard one, and I am not sure which direction we should follow. Could you send me what you have right now, so I could take a look at the scale of changes supporting doubles would introduce?

Either way, I think that we should discuss this extensively before jumping into implementation. Let's switch to Discord to arrange a call and next steps.

We'll update this issue before opening a PR/ PRs related to the subject to keep progress public.

[hsahovic]

We talked with @szymonWojdat and a couple of other developers regarding the next steps on this project.

We concluded that the first thing to do was to separate Battle objects between AbstractBattle and Battle (which could be seen as a singles-oriented object, and could be completed with a similar doubles-oriented object).

After that, we'll do something similar with Player objects in order to go towards having dedicated double objects.

The first corresponding PR is #51

[hsahovic]

@szymonWojdat's branch is ready for review, up to some missing tests.

We are also working with @dmizr to incorporate some of his work. Our goal is to publish version 0.4.0 with double support in August.

[hsahovic]

PR #64 includes @szymonWojdat work into the main repo. Once merged, we'll proceed with additional tests before merging it into master.

[hsahovic]

Done with #86.