refactor: change some classes to use __slots__ Speed up access to and reduce size of some low level classes. A few classes in security.py, rest.py are heavily used. But for all, it prevents adding random properties to lower level classes that people shouldn't be mucking with. While doing this I found some test cases accessing an invalid property name and this change caused the cases to crash. admin.py: Use new method Role.props_dict() and Permission.props_dict() where original code just referenced __dict__ when printing Role/Permission. mlink_expr.py: Add slots to multiple classes. Classes Binary and Unary set real properties/attributes. Classes that inherit from them (Equals, Empty, Not, Or, And) define empty slots tuple to eliminate need for __dict__. Class Expression also gets a slot. rate_limit.py: RateLimit and Gcra classes get slots. A couple of pep8 fixes: sort imports, remove trailing spaces on a line, remove unused noqa comment. rest.py: Add slots to class SimulateFieldStorageFromJson and FsValue classes. The memory savings from this could be useful as well as speedier access to the attributes. security.py: Add slots to Permission class. To prevent conflict between slot limit_perm_to_props_only and the class variable of the same name, rename the class variable to limit_perm_to_props_only_default. Also define method props_dict() to allow other code to get a dict to iterate over when checking permissions. Add slots to class Role along with props_dict() method. Add slots to class Security. Also have to add explicit __dict__ slot to support test override of the hasPermission() method. Add props_dict() method, currently unused, but added for symmetry. support.py: TruthDict and PrioList gets slots. test/test_cgi.py: Fix incorrect setting of permission property. Was setting permissions. So testing may not have been doing what we thought it was. Multiple places found with this typo. Remove setting of permissions in some places where it should have no effect on the test and looks like it was just copypasta. test/test_xmlrpc.py Remove setting of permissions in some places where it should have no effect on the test and looks like it was just copypasta.