fix optics demo on python3

print warning when setuptools is not available

examples/optics/pyoptic.py

@@ -89,7 +89,7 @@ def wlPen(wl):
     return pen
 
 
-class ParamObj:
+class ParamObj(object):
     # Just a helper for tracking parameters and responding to changes
     def __init__(self):
         self.__params = {}

setup.py

@@ -42,6 +42,7 @@ try:
     from setuptools import setup
     from setuptools.command import install
 except ImportError:
+    sys.stderr.write("Warning: could not import setuptools; falling back to distutils.\n")
     from distutils.core import setup
     from distutils.command import install