Change a project

Change a project of yours: its title and description, which presentations are in it ("add" puts presentations of yours at its end, "remove" makes them presentations on their own again) and their order ("order": the slugs of all of its presentations). Links between presentations work only inside a project: a removed presentation's links to the others stop leading anywhere. Access: "access" is the level of the project, which its presentations inherit (the stricter of the project's and the presentation's own level counts); "grant" gives people access to all of it ({"user": name, "role": "view"|"edit"}), "revoke" takes it away (user names).