Better whitelisting of submitted options

We should only allow and persist option keys and values that we use and have sanitized


git-svn-id: https://plugins.svn.wordpress.org/wp-cron-control/trunk@921196 b8457f37-d9ea-0310-8a92-e5e31aec5664
Better escaping on settings page

Use wp_kses_post to strip out potentiall bad HTML and escape default echo.


git-svn-id: https://plugins.svn.wordpress.org/wp-cron-control/trunk@921199 b8457f37-d9ea-0310-8a92-e5e31aec5664