v6.2.1

Fixes

• server: Graph writes check each model that the graph repeats only once for graph control properties, which makes large fetched graphs faster to save, and no longer overflows the stack for graphs that refer back to themselves.
• server: Requires objection ^4.4.1, which resolves the settings of strict graphs once per relation path, so large graphs save faster.
• admin, types: showDialog() accepts dialogs without buttons in its types.
• admin: Forms and sources whose resource function reads its parent set up again: the admin checks whether they declare a resource instead of calling the function without its context. A declared resource function that returns null thus also counts as a resource of its own.