Fix identifierToTag for Python 3
diff --git a/Lib/fontTools/ttLib/__init__.py b/Lib/fontTools/ttLib/__init__.py
index b4f4ff0..732aa52 100644
--- a/Lib/fontTools/ttLib/__init__.py
+++ b/Lib/fontTools/ttLib/__init__.py
@@ -885,7 +885,7 @@
 			tag = tag + ident[i]
 		else:
 			# assume hex
-			tag = tag + bytechr(int(ident[i:i+2], 16))
+			tag = tag + chr(int(ident[i:i+2], 16))
 	# append trailing spaces
 	tag = tag + (4 - len(tag)) * ' '
 	return Tag(tag)