Added logic to deal with the WP Super Cache plugin adding HTML comments at the bottom of feeds. Setting to allow HTML comments with a note have been added to the Feed settings page.

git-svn-id: https://plugins.svn.wordpress.org/powerpress/trunk@876686 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated define to say 5.0.6 beta.

git-svn-id: https://plugins.svn.wordpress.org/powerpress/trunk@876687 b8457f37-d9ea-0310-8a92-e5e31aec5664