Add listing-box-tall class to civicrm.css

Some folks will probably agree that the groups and tags boxes on advanced search are way too short. They use the basic.tpl template file, and they are using the listing-box class from civicrm.css. Since I don't know if that's used elsewhere, I recommend the following class be added to civicrm.css so that others can easily change their custom templates (and we won't have to worry about constantly adjusting this value every time a new release comes out).

/*

• • To allow for taller boxes of groups/tags on Advanced Search page.
    */
    #crm-container .listing-box-tall {
    margin: 0.25em 2.0em -0.5em 0em;
    width: auto;
    height: 15em;
    overflow: auto;
    border: 1px solid #92B6EC;
    }

Alternative would be to have a listing box height configuration in civicrm admin that will dynamically adjust this value.