Prepare for release version 1.6.0
- Add: Setting to customize the mouse-over box shadow
- Update: ManFisher note styling
- Update: Tested with latest nightly build of WordPress 4.1

git-svn-id: https://plugins.svn.wordpress.org/footnotes/trunk@1009659 b8457f37-d9ea-0310-8a92-e5e31aec5664