Implemented Page Criteria: Showcase Categories

I've extended the Core XenForo PAGE criteria for Notices.

When you create a new notice and you click on the Page Criteria Tab, you will now see Showcase Categories as an option (listed below the Page Information options). This allows you to display notices on Showcase Category Pages and on Events within those Category Pages.

NOTE: You CAN NOT combine Nodes, AMS Categories, Showcase Categories, Sportsbook Categories, Gallery Categories (or any other addons page criteria). If you try combining these criteria, the notice won't display anywhere.

NOTE 2: You CAN combine Page Information Criteria however.