Disable 4chan-specific hidden threads sync outside 4chan.

src/Filtering/ThreadHiding.coffee

@@ -12,7 +12,7 @@ ThreadHiding =
       cb:   @node
 
   catalogSet: (board) ->
-    return unless $.hasStorage
+    return unless $.hasStorage and Site.software is 'yotsuba'
     hiddenThreads = ThreadHiding.db.get
       boardID: board.ID
       defaultValue: {}
@@ -20,7 +20,7 @@ ThreadHiding =
     localStorage.setItem "4chan-hide-t-#{board}", JSON.stringify hiddenThreads
 
   catalogWatch: ->
-    return unless $.hasStorage
+    return unless $.hasStorage and Site.software is 'yotsuba'
     @hiddenThreads = JSON.parse(localStorage.getItem "4chan-hide-t-#{g.BOARD}") or {}
     Main.ready ->
       # 4chan's catalog sets the style to "display: none;" when hiding or unhiding a thread.