Shield setup module from accidental setup exec

This might happen when third-parties like analizers import this
module for testing purposes.

setup.py

@@ -162,7 +162,8 @@ for extra_requirements_filename in os.listdir(extra_requirements_dir):
 with open('README.rst', 'r') as readme_file:
     longdesc = readme_file.read()
 
-setup(
+
+setup_params = dict(
     # Use the distutils SDist so that symlinks are not expanded
     # Use a custom Build for the same reason
     cmdclass={
@@ -240,3 +241,12 @@ setup(
     # Installing as zip files would break due to references to __file__
     zip_safe=False
 )
+
+
+def main():
+    """Invoke installation process using setuptools."""
+    setup(**setup_params)
+
+
+if __name__ == '__main__':
+    main()