ifcpatch: small recipe polish

ExtractElements: expand the `query` docstring to cover the exclusion
syntax (`!` on entity classes, `!=` on attribute / pset / material /
classification / location / group facets) and the "seed with a broad
include before subtracting" gotcha — entity-class exclusion does not
auto-seed from "all elements", so a bare `! IfcSlab` query returns
nothing.

FixArchiCADToRevitDoorSwings: guard the `IfcIndexedPolyCurve.Segments`
loop against the IFC4 case where Segments is absent (a polyline
through all coords in declared order). Previously crashed on
`None.__iter__`.

Generated with the assistance of an AI coding tool.

src/ifcpatch/ifcpatch/recipes/ExtractElements.py

@@ -41,7 +41,14 @@ class Patcher(ifcpatch.BasePatcher):
         to a new IFC file. For example, you might want to extract only the walls
         in a model and save it as a new model.
 
-        :param query: A query to select the subset of IFC elements.
+        :param query: A query to select the subset of IFC elements, using the
+            ifcopenshell.util.selector.filter_elements grammar. Supports
+            exclusion (blacklist) via '!' on entity classes and '!=' on
+            attribute / pset / material / classification / location / group
+            facets. Entity-class exclusion does not auto-seed from "all
+            elements", so a bare '! IfcSlab' query returns nothing — start
+            with a broad include (e.g. 'IfcProduct', 'IfcElement') and
+            subtract from it.
         :param assume_asset_uniqueness_by_name: Avoid adding assets (profiles, materials, styles)
             with the same name multiple times. Which helps in avoiding duplicated assets.
             -----
@@ -63,6 +70,12 @@ class Patcher(ifcpatch.BasePatcher):
 
             # Extract all walls and slabs
             ifcpatch.execute({"input": "input.ifc", "file": model, "recipe": "ExtractElements", "arguments": ["IfcWall, IfcSlab"]})
+
+            # Extract everything except slabs (seed with a broad include, then subtract)
+            ifcpatch.execute({"input": "input.ifc", "file": model, "recipe": "ExtractElements", "arguments": ["IfcProduct, ! IfcSlab"]})
+
+            # Extract walls whose Name is not "Foo"
+            ifcpatch.execute({"input": "input.ifc", "file": model, "recipe": "ExtractElements", "arguments": ["IfcWall, attribute.Name != \"Foo\""]})
         """
         super().__init__(file, logger)
         self.query = query

src/ifcpatch/ifcpatch/recipes/FixArchiCADToRevitDoorSwings.py

@@ -190,6 +190,8 @@ class Patcher(ifcpatch.BasePatcher):
         settings.set("dimensionality", ifcopenshell.ifcopenshell_wrapper.CURVES_SURFACES_AND_SOLIDS)
         unit_scale = ifcopenshell.util.unit.calculate_unit_scale(self.file)
         for curve in self.file.by_type("IfcIndexedPolyCurve"):
+            if curve.Segments is None:
+                continue
             if True in [s.is_a("IfcArcIndex") for s in curve.Segments]:
                 shape = ifcopenshell.geom.create_shape(settings, curve)
                 e = shape.edges