Fix feed selection when the max feed score is 0.

This occurs, for example, when searching for “macrumors.com” and adding
to the Feedbin account. All four feeds have a score of 0 since their
source is set as HTMLLink. This would also fix a case in which there are
two feeds: one with a negative score and one with a score of 0.

Since the method uses a Set the feed selected when there are multiple
feeds with an identical maximum score will be random.

Frameworks/Account/FeedFinder/FeedSpecifier.swift

@@ -46,7 +46,7 @@ struct FeedSpecifier: Hashable {
 			return feedSpecifiers.anyObject()
 		}
 		
-		var currentHighScore = 0
+		var currentHighScore = Int.min
 		var currentBestFeed: FeedSpecifier? = nil
 		
 		for oneFeedSpecifier in feedSpecifiers {