+158) Use a single thread to wait for new requests on reused client connections.
+ Currently the thread that handles the first request on a connection
+ stays responsible for the client connect until it gets closed.
+ In case of lots of idle connections lots of waiting threads are used.
+ While it's conceivable that this ineffiency is irrelevant from a
+ performance point of view, using a single thread should reduce Privoxy's
+ memory footprint a bit which may be noticeable in case of multi-user setups
+ with hundreds of idle connections.