Add env varirable CDIFF_OPTIONS to hold default options

CHANGES.rst

@@ -2,6 +2,10 @@
 Change log
 ==========
 
+Version 1.0 (2016-12-31)
+
+  - Use environment variable ``CDIFF_OPTIONS`` to hold default options
+
 Version 0.9.8 (2016-01-16)
 
   - More robust parser to tolerate evil unified diff

cdiff.py

@@ -16,7 +16,7 @@ import select
 import difflib
 
 META_INFO = {
-    'version'     : '0.9.8',
+    'version'     : '1.0',
     'license'     : 'BSD-3',
     'author'      : 'Matthew Wang',
     'email'       : 'mattwyl(@)gmail(.)com',