Merge branch 'master' of ssh://git.carlh.net/home/carl/git/dcpomatic

diff --cc ChangeLog
index d17aa2bdeeb8b154a3e22afcf6e8d236d2973701,5274cacb825b888a2fc652de0a232cc5b5e2dfe3..dd5851e23351c7f8ea0e12d9ac5c8fef9f76f87a
--- 1/ChangeLog
--- 2/ChangeLog
+++ b/ChangeLog
@@@ -1,8 -1,7 +1,12 @@@
 +2017-09-01  Carl Hetherington  <cth@carlh.net>
 +
 +      * Fix corruption of an existing DCP when a new one is made with the same video
 +      asset (#1126).
 +
+ 2017-08-31  Carl Hetherington  <cth@carlh.net>
+ 
+       * Version 2.11.21 released.
+ 
  2017-08-31  Carl Hetherington  <cth@carlh.net>
  
        * Version 2.11.20 released.