Define roadmap

We have a bunch of future features described in the issues list, but currently no plan for when to add those. This has an impact on our IMM score, which reflects the fact that this is likely to reduce confidence in the project.

Define milestones indicating where these features will go.

Review the future-feature issues referenced in the issue list and identify how they should be grouped into milestones. Define milestones that indicate where those features will go, then verify that the roadmap gives a clear plan for the project's future work.

Written by the indexing model from the issue text.