multithreaded download and files that probably should have been in the last

commit

For testing the new iteration, the texture cache disk download was written
into the main thread instead of into the separate threads. Now they're back
in separate threads again.

Also I think some of these files probably should have been in the previous
commit.

app/node/node.h

@@ -164,11 +164,6 @@ public:
    */
   void DisconnectAll();
 
-  /**
-   * @brief Add's unique information about this Node at the given time to a QCryptographicHash
-   */
-  //virtual void Hash(QCryptographicHash* hash, NodeOutput *from, const rational& time);
-
   /**
    * @brief Convert a pointer to a value that can be sent between NodeParams
    */