use --watch, --reprocess, and --masters with --ncpus to process masters in parallel
processing masters in --date mode is broken (L1 objects not updating properly in the loop) for an unknown reason and this is a workaround that fixes that problem
@RussLaher please review and test this before we merge. I changed the call for the L1 part of the masters DRP to include these new flags and it should operate in parallel.