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

__init__.py

@@ -2,10 +2,10 @@
 # this repository contains the full copyright notices and license terms.
 
 from trytond.pool import Pool
-from .purchase_request import *
+from . import purchase_request
 
 
 def register():
     Pool.register(
-        PurchaseRequest,
+        purchase_request.Request,
         module='stock_supply_forecast', type_='model')

purchase_request.py

@@ -2,10 +2,8 @@
 # this repository contains the full copyright notices and license terms.
 from trytond.pool import Pool, PoolMeta
 
-__all__ = ['PurchaseRequest']
 
-
-class PurchaseRequest(metaclass=PoolMeta):
+class Request(metaclass=PoolMeta):
     __name__ = 'purchase.request'
 
     @classmethod
@@ -21,5 +19,5 @@ class PurchaseRequest(metaclass=PoolMeta):
                 ('state', '=', 'done'),
                 ])
         Forecast.create_moves(forecasts)
-        super(PurchaseRequest, cls).generate_requests(*args, **kwargs)
+        super().generate_requests(*args, **kwargs)
         Forecast.delete_moves(forecasts)

setup.py

@@ -79,8 +79,8 @@ setup(name=name,
     keywords='tryton stock supply forecast',
     package_dir={'trytond.modules.stock_supply_forecast': '.'},
     packages=(
-        ['trytond.modules.stock_supply_forecast'] +
-        ['trytond.modules.stock_supply_forecast.%s' % p
+        ['trytond.modules.stock_supply_forecast']
+        + ['trytond.modules.stock_supply_forecast.%s' % p
             for p in find_packages()]
         ),
     package_data={
@@ -95,7 +95,8 @@ 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)',

tests/__init__.py

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