new_IfcBaseClass: use ref for safety

src/ifcopenshell-python/ifcopenshell/ifcopenshell_wrapper.pyi

@@ -1640,7 +1640,7 @@ def less(arg1, arg2): ...
 def line_segments_to_polygons(s, eps, segments): ...
 def map_shape(settings, instance): ...
 def nary_union(sequence): ...
-def new_IfcBaseClass(schema_identifier: str, name: str) -> entity_instance: ...
+def new_IfcBaseClass(file: file, name: str) -> entity_instance: ...
 def open(fn: str, readonly: bool = False, logger=None) -> file: ...
 def polygons_to_svg(*args): ...
 def read(data): ...

src/ifcwrap/IfcParseWrapper.i

@@ -1045,8 +1045,8 @@ from .entity_instance import entity_instance_mixin as _entity_instance_mixin_bas
 		return IFCOPENSHELL_VERSION;
 	}
 
-	express::Base new_IfcBaseClass(ifcopenshell::file* file, const std::string& name) {
-        return file->create(file->schema()->declaration_by_name(name));
+	express::Base new_IfcBaseClass(ifcopenshell::file& file, const std::string& name) {
+        return file.create(file.schema()->declaration_by_name(name));
 	}
 %}