This is an old repository kept around for legacy support. If you want the save editor, look here.
Sky Editor is a plugin-based editor for Pokemon Mystery Dungeon saves and ROMs, but because it is plugin based, the sky is the limit to what it can do.
The infrastructure and relevant documentation is still in the works, but related myget feed needed for building can be found here: https://www.myget.org/F/skyeditor/api/v3/index.json
Plugin development is not ready yet, but when it is, there will be a link here to a guide on how to get started. Using the code and the above myget feed would allow a developer to make a plugin now, but is not advised because the core libraries could drastically change their interface in the future.