Fix flake8 errors and warnings

We add the flake8 configuration used so we ensure everyone uses the same.
We remove the usage of __all__ for non public API.
When possible, we rationalize the class name according to its __name__ and module.

issue9082
review297061002

.flake8

@@ -0,0 +1,2 @@
+[flake8]
+ignore=E123,E124,E126,E128,W503

configuration.py

@@ -5,9 +5,6 @@ from trytond.model import fields
 from trytond.pyson import Eval
 
 
-__all__ = ['Configuration', 'ConfigurationDefaultAccount']
-
-
 class Configuration(metaclass=PoolMeta):
     __name__ = 'account.configuration'
 

product.py

@@ -16,11 +16,6 @@ from trytond.modules.company.model import (
 
 from .exceptions import AccountError, TaxError
 
-__all__ = ['Category', 'CategoryAccount',
-    'CategoryCustomerTax', 'CategorySupplierTax',
-    'Template', 'Product', 'account_used', 'template_property',
-    'TemplateAccountCategory', 'TemplateCategoryAll']
-
 
 def account_used(field_name, field_string=None):
     if field_string is None:

setup.py

@@ -79,8 +79,8 @@ setup(name=name,
     keywords='tryton account product',
     package_dir={'trytond.modules.account_product': '.'},
     packages=(
-        ['trytond.modules.account_product'] +
-        ['trytond.modules.account_product.%s' % p for p in find_packages()]
+        ['trytond.modules.account_product']
+        + ['trytond.modules.account_product.%s' % p for p in find_packages()]
         ),
     package_data={
         'trytond.modules.account_product': (info.get('xml', [])
@@ -93,7 +93,8 @@ setup(name=name,
         'Intended Audience :: Developers',
         'Intended Audience :: Financial and Insurance Industry',
         'Intended Audience :: Legal Industry',
-        'License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)',
+        'License :: OSI Approved :: '
+        'GNU General Public License v3 or later (GPLv3+)',
         'Natural Language :: Bulgarian',
         'Natural Language :: Catalan',
         'Natural Language :: Chinese (Simplified)',

tests/__init__.py

@@ -2,7 +2,7 @@
 # this repository contains the full copyright notices and license terms.
 
 try:
-    from trytond.modules.account_product.tests.test_account_product import suite
+    from trytond.modules.account_product.tests.test_account_product import suite  # noqa: E501
 except ImportError:
     from .test_account_product import suite