Replaces the plugin-only set_slices/set_fill_surfaces/set_lslices mutators with a
faithful, mutable binding of the core geometry types, so a plugin edits the slicing
graph through the same object model the C++ code uses.
- Point, Polygon, ExPolygon, Surface and SurfaceCollection gain constructors,
writable accessors (contour/holes, set/append/clear, filter_by_type), transforms
(rotate/scale/translate), boolean ops and offset. Polygon exposes a zero-copy
writable numpy view via a make_writable_rows helper.
- LayerRegion.slices/fill_surfaces stay read-only refs but are now live,
in-place-editable SurfaceCollections; Layer.make_slices() re-derives the islands
and refreshes lslice bounding boxes.
- Rewrites the Inset and Twistify samples on the new API (in-place ExPolygon
transforms, ExPolygon.offset, SurfaceCollection.set), dropping their numpy
dependency; each touched layer calls make_slices() so downstream steps see the
edited footprint. Adds tests covering in-place edits through a live collection.
BREAKING CHANGE: set_slices/set_fill_surfaces/set_lslices and the internal
parse_expolygon(_list)/surfaces_from_py helpers are removed. Plugins mutate through
the class API (SurfaceCollection.set/append/clear, Polygon.set_points/append,
ExPolygon.set_holes) instead.
Adds PluginHostSlicing, which registers the print-graph data model (Print,
PrintObject, Layer, LayerRegion, Surface, ExPolygon, extrusions, ...) into the
orca.host submodule in the same raw-class style as PluginHostApi's Model/Preset
graph, with shared helpers in PluginBindingUtils. SlicingPipelinePluginCapability
is trimmed to the capability surface (the standalone SlicingNumpy helper is folded
away). Adds the Twistify example plugin next to Inset and broadens the binding,
hook, and plugin-install tests.
