Fix incompatibility with isort configuration file

[guewen]

The checker uses 'isort' to know if an imported library is in the
standard library or is a third party library. Then, for third party
libraries, the check will fail if it is not declared in the addon
manifest's external dependencies.

Some python modules are known to be used by Odoo and do not need to
be declared in the external dependencies. These libraries are listed
in a whitelist of the checker.

isort's SortImports class is initialized with an argument
'known_standard_library' where the whitelist is passed. It forces
isort to consider them as standard library, thus ignoring the check.

However, when the project's directory contains an '.isort.cfg' file,
because the project uses isort to actually sort the imports in the code,
the file usually contains a line such as:

[settings]
known_third_party = dateutil,openupgradelib,pkg_resources,psycopg2,requests,setuptools,urllib2,yaml

This line is necessary for isort to move the imports at the expected
place, after the standard imports.

When this file is present, the isort's 'place_module()' method will
consider it when called by the checker, and will consider the
whitelisted modules to be third party instead of the "expected" standard
library.

This commit directly checks if the module is in the whitelist, so we
avoid the confusion. isort is now only used to distinguish the standard
and third party which are not in the whitelist.

Fixes #247

[sbidoul]

@guewen BTW, do you know that Odoo 13 now allows referencing PyPI distribution names in python depends rather than the import name? It's the recommended way to do it.

Sorry I don't have time to review this PR right now, I don't know if this changes something or not.

[guewen]

Yes, and this checker doesn't take this into account. A similar check than odoo/odoo#25549 should be added in

pylint-odoo/pylint_odoo/checkers/modules_odoo.py

Lines 379 to 380 in d8bf90d

	if module_name not in py_ext_deps and \
	module_name.split('.')[0] not in py_ext_deps:

Should be the matter of another PR

[moylop260]

👍