Pattern fills on shape layers rendered transparent because the vector
renderer had no access to the document's pattern table. Add
Paint::Pattern, Paint::from_fill_with_patterns,
CompiledShape::with_patterns and render_shape_with_patterns, which
resolve a pattern by id or name and sample it in the document's colour
mode, for the fill and the stroke independently.
The compositor's fill/stroke split (used for clipped layers and interior
effects) now renders with the same patterns and colour mode on CPU and
GPU, and its cache key covers the referenced pattern tiles.
Refs #2496
Skyfuller1303