Move to WrappedUnions.jl for multiagent macro

[Tortar]

WrappedUnions.jl is the successor of LightSumTypes.jl, and it is much better in many aspects.

[Datseris]

What's the motivation for making a new package? Will this a breaking change?

[Tortar]

The package has a totally different interface, so using that directly is a breaking change. In the case of Agents, it won't because we have a different interface on top of the one of the package which we can preserve.

[Datseris]

Right, that's true, but what is the motivation or the aspects where it is much better?

[Tortar]

The user is in total control of the union-splitting behaviour, before it was just on getproperty/setproperty!, while with this, through the @unionsplit macro, it allows to create branches automatically for "wrapped" types for any function. In practice, this means you can totally control the type-stabilizing properties of the approach, unlike before. Also it is much less opinionated, it doesn't ship more than the essential.

[Datseris]

So you can for example make a specialized behavior for agent_step! let's say? And this helps with performance in ways that the previous approach could not achieve? (the latter part is not clear to me: is this new approach more performant, ort is it just the same functionality and performance but just cleaner, with less source code?)

[Tortar]

yes, we can also improve the performance of agent_step! in ways not possible before. E.g. this would be better than before: agent_step!(a::MultiAgent) = @unionsplit agent_step!(a)