Make inspect.py file compatible to run with python2 and python3 (#748)

Signed-off-by: Parag A Nemade <pnemade@fedoraproject.org>

Lib/fontTools/inspect.py

@@ -8,8 +8,14 @@
 from __future__ import print_function, division, absolute_import
 from fontTools.misc.py23 import *
 from fontTools import misc, ttLib, cffLib
-import pygtk
-pygtk.require('2.0')
+try:
+    from gi import pygtkcompat
+except ImportError:
+    pygtkcompat = None
+
+if pygtkcompat is not None:
+    pygtkcompat.enable()
+    pygtkcompat.enable_gtk(version='3.0')
 import gtk
 import sys