basic swap file search in Metric#values_in

  // note that time0 > time1! this method is threadsafe

  def values_in(time0: Long, time1: Long) : List[(Long, Double)] = {

    val lst = ListBuffer[(Long, Double)]()

    var found_start : Long = 0

    // FIXPAUL: skip n flush_intervals if time0 is older than now, maybe

    // skip rbuf_search completely

          // collect all matching items

          lst += cur

          if (found_start == 0)

            found_start = cur._1

          // if we are looking only for a single value we can exit now

          if (time1 == 0)

            return lst.toList

    swap_pos -= (rbuf_seek_pos * swap.BLOCK_SIZE)

    while (swap_pos > 0) {

      swap_chunk.clear

      // load the next chunk of samples from the swapfile

      swap_pos = swap.load_chunk(swap_pos, swap_chunk)

        // skip if we already saw this sample in the rbuf search

        if (cur._1 < rbuf_last) {

          println("LOAD_SWAP", cur)

        }

          // if we are already beyond time1 we can exit

          if (time1 != 0 && (cur._1 < time1))

            return lst.toList

          // if we are only looking for a single value and already beyond time0

          // plus flush_interval and didnt find a value yet, we can exit

          if (time1 == 0 && (cur._1 < (time0 - key.flush_interval)))

            return lst.toList

          // check if we found the start of the range yet

          if (cur._1 <= time0 && ((cur._1 >= time1) || time1 == 0)) {

            // collect all matching items

            lst += cur

            // if we are looking only for a single value we can exit now

            if (time1 == 0)

              return lst.toList

          }

        }

      }

      swap_chunk.clear

    }

    lst.toList

  }