Merge branch 'master' of https://github.com/pgajdos/pyclipper into pgajdos-master

setup.py

@@ -97,6 +97,6 @@ setup(
        'cython>=0.28',
        'setuptools_scm>=1.11.1',
     ] + pytest_runner,
-    tests_require=['unittest2', 'pytest'],
+    tests_require=['pytest'],
     cmdclass=cmdclass,
 )

tests/test_pyclipper.py

@@ -4,7 +4,10 @@ Tests for Pyclipper wrapper library.
 """
 
 from __future__ import print_function
-from unittest2 import TestCase, main
+try:
+  from unittest2 import TestCase, main
+except ImportError:
+  from unittest import TestCase, main
 import sys
 
 if sys.version_info < (3,):