Prepare and release v4

[VulpusMaximus]

Release v4 will contain rewrites of all of the existing commands, potentially some entirely new ones, and all actually working unlike the unreleased v3. See the project board for how that is going, all taking place under the revisit branch.

Once the update is feature complete, and all of the feature issues have been marked as "Done", the addon will be tested in various scenarios, on various maps, to check that all of the commands work and don't cause any other problems, before they are released to the main branch as v4.0.0.

This issue will be used to keep track of the progress on the overall release.