Adds Help & Instructions screen to Options.

Reworks Options menus, tabs, and slug structure.  Shortens slugs
significantly and adds submenus that function correctly with the
pre-existing tabs.

Adds ability to control the number of testimonials that appear per
slide.  Defaults to 1 testimonial per slide.

Re works some code to better function groupings, shortening overall code
base.

git-svn-id: https://plugins.svn.wordpress.org/easy-testimonials/trunk@987470 b8457f37-d9ea-0310-8a92-e5e31aec5664