Monitor: only add pause on request
Monitor: put gpsstart up a bit
TimeSeriesMonitor: add minor grid for logy
SpectrumMonitor: add FFT params to suptitle
NDSDataSource.backfill: added method to get old data

    - uses a combination of fetch() and iterate() to try and get all
      data, the second iterate doesn't do very much (I think)
Monitor.save: moved save commands upstream
Monitor._clock: added run() data to wait for nice clock time

    - doesn't work properly due to time taken to complete iteration,
      needs to be fixed
gwdv: added backfill