Introduce speed parameter

git-svn-id: https://plugins.svn.wordpress.org/wp-photonav/trunk@1034764 b8457f37-d9ea-0310-8a92-e5e31aec5664
Polish and clean-up

git-svn-id: https://plugins.svn.wordpress.org/wp-photonav/trunk@1034765 b8457f37-d9ea-0310-8a92-e5e31aec5664
Prepared for release

git-svn-id: https://plugins.svn.wordpress.org/wp-photonav/trunk@1034766 b8457f37-d9ea-0310-8a92-e5e31aec5664