Merge branch 'master' of https://github.com/gber/chevron into gber-master

diff --cc chevron/renderer.py
index a1dca72dc2b3566d0bfd38bb5b4acac07aa87fc8,c66471d04d8a1a112b23a1342f06051fccee39f3..075eec6e636cb1c2fed3ef6bea01fceae5751458
--- 1/chevron/renderer.py
--- 2/chevron/renderer.py
+++ b/chevron/renderer.py
@@@ -1,7 -1,9 +1,11 @@@
  # -*- coding: utf-8 -*-
  
 +import io
 +
+ try:
+     from collections.abc import Sequence, Iterator, Callable
+ except ImportError:  # python 2
+     from collections import Sequence, Iterator, Callable
  try:
      from .tokenizer import tokenize
  except (ValueError, SystemError):  # python 2