* Replace the Artboard struct with a Table<Table<Graphic>> shape
* Remove the never-functional, seemingly unneeded migrate_type_descriptor_names due to typo
* Allow negative artboard sizes
* Feature-gate serde derives behind cfg_attr in all runtime node graph type crates
* Refactor Table to move its hard-coded fields into an attributes field
* Encapsulate TableRow/TableRowRef/TableRowMut attribute fields behind accessor methods
* Remove TaggedValue::GraphicUnused
* Refactor Table<T> to use dynamic attributes instead fixed names
* Fix code review soundness concerns
* Add todo work
* Replace row-oriented Table<T> API with column-oriented access
* Fix attribute propagation bugs
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* Add checkered transparency rendering to infinite canvas and artboards
* Enable artboard clipping by default
* Make new infinite canvas documents begin with a white background layer
* Remove the export dialog's transparency option now that it's redundant
* Make exporting transparent JPGs use white not black
* Code review