issues auto generating rna docs

- add a warning when an operator name is NULL, set it to a dummy name to prevent crash. POSE_OT_constraints_clear had its name commented (not sure why)
- rna_Object_parent_type_itemf wasnt checking for context being NULL, needed for docs else it crashes.
- bpy.ops.add/remove didnt show up in a dir(bpy.ops)

source/blender/editors/object/editconstraint.c

@@ -1011,7 +1011,7 @@ static int pose_constraints_clear_exec(bContext *C, wmOperator *op)
 void POSE_OT_constraints_clear(wmOperatorType *ot)
 {
 	/* identifiers */
-	//ot->name = "Clear Constraints";
+	ot->name = "Clear Constraints";
 	ot->idname= "POSE_OT_constraints_clear";
 	ot->description= "Clear all the constraints for the selected bones.";