* Unify the scheduler's "build" and "extract" queues into a single

 * Unify the scheduler's "build" and "extract" queues into a single
   "jobs" queue.

 * Add support for logging fetches to /var/log/emerge-fetch.log when
   --jobs is enabled. Previously this log was only used for
   the parallel-fetch feature but now it's also used for --jobs.
   The scheduler's "prefetch" queue has been renamed to "fetch" since
   it's not exclusively used for parallel-fetch anymore.

 * Pass the "background" parameter from Binpkg in to the BinpkgFetcher
   instance, to send output to emerge-fetch.log instead of stdout.

svn path=/main/trunk/; revision=10999