Plug-ins: painted pieces keep their swatches in Pathfinder and baked art

Pathfinder effects, compound shapes, Expand Appearance and pattern
expansion now pass the document to the effects they evaluate, so a
painted piece that names a swatch or pattern takes part as drawn instead
of being refused. A path with a painted effect takes part in Pathfinder
and compound shapes as its pieces, each with its own paint, inside the
path's opacity and blend mode.

The renderer's kept effect art and live evaluations now count the
document's swatch and pattern names for objects with a plug-in effect,
so deleting or restoring a swatch a piece names redraws the object.

docs/plugins.md

@@ -421,7 +421,9 @@ is a piece drawn by itself, in the order returned, with paints of its own:
 - An effect on a fill (`_context.item` `{"fill": i}`) returns only `fills`, which replace that fill on each piece; an
   effect on a stroke returns only `strokes`. The object's other fills and strokes stay where they are.
 - The effects after it in the stack apply to the pieces together, the reference box being the bounds of all of them.
-  Bounds, hit tests and raster effects use the pieces as they are drawn. Each piece counts against the budget of the
+  Bounds, hit tests, raster effects, Pathfinder effects, compound shapes and Envelope Options › Distort Appearance use
+  the pieces as they are drawn. For an effect on a fill or stroke, Pathfinder effects and compound shapes use the
+  object's path, as they do for every other effect on a fill or stroke. Each piece counts against the budget of the
   object's geometry effects as well as its anchors, so all the painted effects in a stack make at most 100,000 pieces
   together; a run whose pieces would pass the budget draws its input as it was.
 - The result is checked whole before any of it is drawn: the limits of a filter's output (100,000 objects, 4,000,000