Adds template and command line options for trend type and auto trend type select thresholds.

Adds the --auto, --raw, --sec, --min, --auto-raw-sec, and --auto-sec-min options:

pthomas@debian:~/files/gitlab/ndscope$ python3 -m ndscope --help
usage: 
ndscope [<options>]
ndscope [<options>] <channel> ...
ndscope [<options>] .yaml|.stp|.xml|.txt|-
ndscope [<options>] .hdf5|.h5
ndscope -h|--help|--usage|--version

Next generation NDS oscilloscope

optional arguments:
  -t TIME, --time TIME  time boundary (GPS or natural language), may specify one or two)
  -w TIME_WINDOW, --window TIME_WINDOW, --time-window TIME_WINDOW
                        time window scalar or tuple, in seconds
  --auto                auto select trend type
  --raw                 raw trend type
  --sec                 second trend type
  --min                 minute trend type
  --auto-raw-sec AUTO-RAW-SEC
                        auto select trend type raw/second threshold
  --auto-sec-min AUTO-SEC-MIN
                        auto select trend type second/minute threshold
  -g, --grid            arrange channels in a grid of plots (default)
  -k, --stack           arrange channels in a vertical stack of plots
  -s, --single          all channels in a single plot
  -l, --table           subplot table layout (period/comman in channel list starts new colum/row)
  --title TITLE, --window-title TITLE
                        application window title
  --light               light color mode (black-on-white plots)
  --dark                dark color mode (white-on-black plots) [default]
  --size WIDTH HEIGHT   specify initial window size
  --nds HOST[:PORT]     NDS server [nds.ligo.caltech.edu:31200]
  --gen-template        generate YAML template, dump to stdout, and exit
  --single-shot PATH    export initial plot/data then exit (see export options in usage)
  --version             print version and exit
  --usage               print more detailed usage information and exit

Closes issue #255 (closed) and #211 (closed).