Tidy up cropping code

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@968290 b8457f37-d9ea-0310-8a92-e5e31aec5664
Escape admin setting fields

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@968291 b8457f37-d9ea-0310-8a92-e5e31aec5664