max 2 cores on unix system

Author: Teseo Schneider

setup.py

@@ -67,7 +67,7 @@ def build_extension(self, ext):
                 cmake_args += ['-A', 'x64']
             build_args += ['--', '/m']
         else:
-            build_args += ['--', '-j']
+            build_args += ['--', '-j2']
 
         env = os.environ.copy()
         env['CXXFLAGS'] = '{} -DVERSION_INFO=\\"{}\\"'.format(env.get('CXXFLAGS', ''),self.distribution.get_version())