py23 Use new-style classes

Such that we get the same semantics in both Python 2 and 3.
diff --git a/Lib/fontTools/misc/xmlWriter.py b/Lib/fontTools/misc/xmlWriter.py
index 11e8289..6862e91 100644
--- a/Lib/fontTools/misc/xmlWriter.py
+++ b/Lib/fontTools/misc/xmlWriter.py
@@ -9,7 +9,7 @@
 INDENT = "  "
 
 
-class XMLWriter:
+class XMLWriter(object):
 	
 	def __init__(self, fileOrPath, indentwhite=INDENT, idlefunc=None):
 		if not hasattr(fileOrPath, "write"):