pycodegen: make generated objects comparable #592
Description
At the moment, objects generated by python codegen do not implement __eq__ and __hash__ methods. Therefore, equivalence and membership tests fail for two identical copies of an object. This can create some issues and unwanted behaviors, for example here.
A basic rule could be to generate __eq__ and __hash__ methods that only consider Schema SALAD fields, i.e. excluding extension_fields and loadingOptions. This should solve the majority of cases (maybe all?).