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

carrier.py

@@ -3,8 +3,6 @@
 from trytond.model import fields
 from trytond.pool import PoolMeta
 
-__all__ = ['Carrier']
-
 
 class Carrier(metaclass=PoolMeta):
     __name__ = 'carrier'

setup.py

@@ -87,8 +87,8 @@ setup(name=name,
     keywords='tryton purchase shipment cost',
     package_dir={'trytond.modules.purchase_shipment_cost': '.'},
     packages=(
-        ['trytond.modules.purchase_shipment_cost'] +
-        ['trytond.modules.purchase_shipment_cost.%s' % p
+        ['trytond.modules.purchase_shipment_cost']
+        + ['trytond.modules.purchase_shipment_cost.%s' % p
             for p in find_packages()]
         ),
     package_data={
@@ -103,7 +103,8 @@ setup(name=name,
         'Intended Audience :: Financial and Insurance Industry',
         'Intended Audience :: Legal Industry',
         'Intended Audience :: Manufacturing',
-        '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)',

stock.py

@@ -10,8 +10,6 @@ from trytond.transaction import Transaction
 
 from trytond.modules.product import price_digits
 
-__all__ = ['ShipmentIn', 'Move']
-
 
 class ShipmentIn(metaclass=PoolMeta):
     __name__ = 'stock.shipment.in'

tests/__init__.py

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

tests/test_purchase_shipment_cost.py

@@ -28,7 +28,8 @@ def suite():
             checker=doctest_checker,
             optionflags=doctest.REPORT_ONLY_FIRST_FAILURE))
     suite.addTests(doctest.DocFileSuite(
-            'scenario_purchase_shipment_cost_with_account_stock_anglo_saxon.rst',
+            'scenario_purchase_shipment_cost_'
+            'with_account_stock_anglo_saxon.rst',
             tearDown=doctest_teardown, encoding='utf-8',
             checker=doctest_checker,
             optionflags=doctest.REPORT_ONLY_FIRST_FAILURE))