- introduced blocking queues in CrawlStacker to make it ready for concurrency
- added a second busy thread for the CrawlStacker
The CrawlStacker is multithreaded. It shall be transformed into a BlockingThread in another step.
The concurrency of the stacker will hopefully solve some problems with cases where DNS blocks.
git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@5395 6c8d7289-2bf4-0310-a012-ef5d649a1542