Leverage `selection-actions` as a list

[aadcg]

The documentation of selection-actions suggests that it could be a list, but there's no mechanism to handle it as a list of multiple elements.

Also, I can't think of an example where it could be used as a list. Anyone? @Ambrevar @aartaka @jmercouris @pdelfino

[Ambrevar]

Aaaah, thank you for bringing this up, completely forgot about it and the "TODO:" comment disappeared a while ago when refactoring.

What was originally meant with this is the ability to run multiple "persistent actions" (in Helm parlance -- actions that don't close the prompt buffer).

Indeed, we are missing a way to run these actions. I'll work on it.

[aadcg]

Ok! It makes perfect sense now. It's not a priority :)

[aadcg]

@Ambrevar do you still think this is a priority for 3.0? I think this could arrive later during the 3-series.

[Ambrevar]

I'm unsure it would break the API. That said, it's easy to implement, so I wouldn't worry too much about it.