Bump version number for development version

git-svn-id: https://plugins.svn.wordpress.org/subscribe2/trunk@901875 b8457f37-d9ea-0310-8a92-e5e31aec5664
Improve digest email processing and make use of 's2_custom_keywords' more appropriate also

git-svn-id: https://plugins.svn.wordpress.org/subscribe2/trunk@901876 b8457f37-d9ea-0310-8a92-e5e31aec5664