If Points History is visible for other members it is visible for visitors as well.

git-svn-id: https://plugins.svn.wordpress.org/mycred/trunk@757720 b8457f37-d9ea-0310-8a92-e5e31aec5664
Replaced get_users() with custom database query in order to handle large queries.

git-svn-id: https://plugins.svn.wordpress.org/mycred/trunk@757721 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added transient for rank count.

git-svn-id: https://plugins.svn.wordpress.org/mycred/trunk@757722 b8457f37-d9ea-0310-8a92-e5e31aec5664