Added Thread Prefixes for Classified Ads

[Josh]

I've added 3 thread prefixes for our For Sale/Wanted subforum. You can now choose "Asia" "Europe" or "USA" to make it easier for people to find regional threads. You can still choose none of the above and specify in your thread title or the thread itself. If we have high demand for other regions, it's simple to add more, just let me know!
Hope this is useful!