Fix support for Sphinx 1.3

doc/source/conf.py

@@ -12,6 +12,7 @@
 # serve to show the default.
 
 import sys, os
+import sphinx
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
@@ -50,7 +51,10 @@ else:
 templates_path = ['_templates']
 
 # The suffix of source filenames.
-source_suffix = '.txt'
+if sphinx.__version__.startswith('1.3'):
+    source_suffix = ['.txt']
+else:
+    source_suffix = '.txt'
 
 # The encoding of source files.
 #source_encoding = 'utf-8-sig'