Removing deprecated line of code to avoid debug warning in WP

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-to-database-extension/trunk@1028969 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added more protection around input variables

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-to-database-extension/trunk@1028971 b8457f37-d9ea-0310-8a92-e5e31aec5664
Version 2.8.18

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-to-database-extension/trunk@1028973 b8457f37-d9ea-0310-8a92-e5e31aec5664
Stable tag: 2.8.18

git-svn-id: https://plugins.svn.wordpress.org/contact-form-7-to-database-extension/trunk@1028977 b8457f37-d9ea-0310-8a92-e5e31aec5664