Update slide menu_order on save

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@774074 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update nivo_slider_parameters filter

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@774076 b8457f37-d9ea-0310-8a92-e5e31aec5664