Move critical requirements to setup.py (#13)

* Move critical requirements to setup.py

Prehistoric setuptools ignores several setup.cfg flags

* Move URLs to setup.cfg

This attributes are parsed by modern setuptools only, so reduce warnings

Author: penguinolog

setup.cfg

@@ -1,18 +1,13 @@
+[metadata]
+name = Advanced-Descriptors
+project_urls =
+    Bug Tracker = https://github.com/python-useful-helpers/advanced-descriptors/issues
+    Documentation = https://advanced-descriptors.readthedocs.io/
+
 [options]
 zip_safe = False
 packages = find:
 
-# While setuptools cannot deal with pre-installed incompatible versions,
-# setting a lower bound is not harmful - it makes error messages cleaner. DO
-# NOT set an upper bound on setuptools, as that will lead to uninstallable
-# situations as progressive releases of projects are done.
-# Blacklist setuptools 34.0.0-34.3.2 due to https://github.com/pypa/setuptools/issues/951
-# Blacklist setuptools 36.2.0 due to https://github.com/pypa/setuptools/issues/1086
-setup_requires =
-    setuptools >= 21.0.0,!=24.0.0,!=34.0.0,!=34.0.1,!=34.0.2,!=34.0.3,!=34.1.0,!=34.1.1,!=34.2.0,!=34.3.0,!=34.3.1,!=34.3.2,!=36.2.0
-
-python_requires = >=2.7.5,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*
-
 [bdist_wheel]
 # This flag says that the code is written to work on both Python 2 and Python
 # 3. If at all possible, it is good practice to do this. If you cannot, you

setup.py

@@ -240,16 +240,22 @@ def get_simple_vars_from_src(src):
         for name, email in variables['__maintainers__'].items()
     ),
     url=variables['__url__'],
-    project_urls={
-        "Bug Tracker": "https://github.com/python-useful-helpers/advanced-descriptors/issues",
-        "Documentation": "https://advanced-descriptors.readthedocs.io/",
-    },
     version=variables['__version__'],
     license=variables['__license__'],
     description=variables['__description__'],
     long_description=long_description,
     classifiers=classifiers,
     keywords=keywords,
+    python_requires='>=2.7.5,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*',
+    # While setuptools cannot deal with pre-installed incompatible versions,
+    # setting a lower bound is not harmful - it makes error messages cleaner. DO
+    # NOT set an upper bound on setuptools, as that will lead to uninstallable
+    # situations as progressive releases of projects are done.
+    # Blacklist setuptools 34.0.0-34.3.2 due to https://github.com/pypa/setuptools/issues/951
+    # Blacklist setuptools 36.2.0 due to https://github.com/pypa/setuptools/issues/1086
+    setup_requires="setuptools >= 21.0.0,!=24.0.0,"
+                   "!=34.0.0,!=34.0.1,!=34.0.2,!=34.0.3,!=34.1.0,!=34.1.1,!=34.2.0,!=34.3.0,!=34.3.1,!=34.3.2,"
+                   "!=36.2.0",
     install_requires=required,
     package_data={
         'advanced_descriptors': [