RFC: API Change for Targets

[adapap]

*Not working on refactoring tests until there is a consensus on API changes

This PR proposes a new API based around the fact that target structs will be passed around, which are simply a composite key of (party, slot) of an active? Pokemon. The reasons for this proposal include:

• Pointer/memory management is difficult
• Easier to validate turns and transactions
• Hashable key
• Less data passed around to/from client

Potential/only? drawback:

• Must retrieve Pokemon pointer from battle as-needed
  • This is not an expensive operation, as it is a constant-time composite key lookup. This has the side effect of always ensuring that Pokemon have updated data, including if they are switched out, fainted, etc.

Summary of API changes

• Moved pre, during, and post-round logic to a new file: battle_round.go
• target is now defined as struct{party: uint, slot: uint} (negative indices will not occur!)
• All transactions use target objects instead of pointers
• party.activePokemon is now a map[uint]uint instead of a map to pointers to easily implement SwitchTurn in the future
• BattleContext is reworked to lazily compute values: Self(), Allies(), Opponents(), Targets()

Removed the following helper methods as they are redundant, replaced, or otherwise disposable:

• battle.getPokemonInBattle
• battle.getTarget
• battle.GetTargetsRef
• battle.getContext, battle.GetRoundContext renamed to battle.GetBattleContext
• battleParty.GetActivePokemon (this one might be needed still or replaced)

Closes #362

[dyc3]

It would be a good idea to at least refactor the test in agent_test to make sure you're making deep copies.

Can you give an example of what an Agent implementation would look like now? Try the smarterAgent in benchmark_test

[adapap]

@dyc3 Modified a chunk of tests, and the example in benchmark, to use the new API. Not much actually has to change on the implementation end - the benefits are mostly internal organization.

I want to double check that the copy is actually a copy passed to agents if you could verify that.