indexers implementation is now separated from settings/definition

so we can have multiple newznab definitions.

NzbDrone.Core/Indexers/IIndexer.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+
+namespace NzbDrone.Core.Indexers
+{
+    public interface IIndexer
+    {
+        string Name { get; }
+
+        IEnumerable<IndexerDefinition> DefaultDefinitions { get; }
+
+        IndexerDefinition InstanceDefinition { get; set; }
+
+        IEnumerable<string> RecentFeed { get; }
+
+        IParseFeed Parser { get; }
+
+        IEnumerable<string> GetEpisodeSearchUrls(string seriesTitle, int seasonNumber, int episodeNumber);
+        IEnumerable<string> GetDailyEpisodeSearchUrls(string seriesTitle, DateTime date);
+        IEnumerable<string> GetSeasonSearchUrls(string seriesTitle, int seasonNumber);
+        IEnumerable<string> GetPartialSeasonSearchUrls(string seriesTitle, int seasonNumber, int episodeWildcard);
+    }
+}