[Plugin: WPMU Infinite SEO Addon] check if infinite seo is installed

hello,

it might be a good idea to add some function that checks if the mail plugin is installed before activating the addon. people can install the addon randomly and have no idea they need anything else, but that causes a fatal error and you have to delete it manually.

thanks

https://www.ads-software.com/extend/plugins/wpmu-dev-seo-addon/