Reference Facepunch.ActionGraphs, NodeEditor abstraction (#1311) * Allow references to Facepunch.ActionGraph in editor code * Add some basic node definitions * Expose TypeLibrary members as nodes * Refactor NodeGraph to support dynamic nodes * Hotload: fix before / after constraints on upgrader ordering * TypeLibrary.GetSerializedObject overload accepting a getter * Add [Flags] to DockProperty * Allow custom exception stack trace inspectors * Skip HideInEditor properties in ControlSheets