Filter pattern replacement

[cquijano]

This patch is useful to get tv shows in folders (as Kodi need for example).
I have some like this in my automatic.conf

filter = { 
           pattern => "(.*)(\d+)x(\d+)"
           folder  => "/storage/videos/tvshows/\1"
           feedid  => 1                 
         }

So when a pattern mach, the tv show is added to it's folder.

[cquijano]

I think this fix the issues:

• Sorry for bad comments, I wrote them when I was reading the code, my bad.
• I need download_folder_reg and download_folder to avoid memory leak or segmentations faults.

if(isMatch(session->filters, item->name, feedID, &download_folder, &filter_pattern)) 
....
download_folder_reg = rewriteURL(item->name, filter_pattern, download_folder);

In first line, download_folder can't be freed because is only a ref , but in the second line download_folder_reg, must be freed, so I need 2 vars. (Or I think so)