* improved: user input sanitization

git-svn-id: https://plugins.svn.wordpress.org/simple-course-creator-front-display/trunk@940196 b8457f37-d9ea-0310-8a92-e5e31aec5664
update stable tag

git-svn-id: https://plugins.svn.wordpress.org/simple-course-creator-front-display/trunk@940197 b8457f37-d9ea-0310-8a92-e5e31aec5664