[Dart-users] minor updates to the GPS converter

[Nancy Collins]

  hi dart-users,

i just committed some minor changes to the gps converter,
shell scripts, and documentation.

the most visible user change is that the 'obs_window' is no
longer supported, and the converter doesn't need to read a
time string from standard input anymore.  it will simply convert
all the given input files into a single output obs_sequence file.

if you wish to do time windowing, you can do that in one of
several ways:

- only download input files with the right timestamps (the download
     scripts already support this option)
- download all data and convert it, and then use the obs_sequence_tool
     to cut the files into particular windows
- use the wrf preprocessor time windowing options to select a subset
     of the data.

if you update to this code you will need to remove 'obs_window' from
your input namelist, and while it won't hurt, you don't need to compute
a time string and echo that into the converter's standard input.

i've moved all the download and convert scripts from work into its own
shell_scripts directory so it's easier to see what is there.  the README
moved as well and has been updated to match these changes.

i've downloaded a couple example netcdf files so you can try out the
converter even before you get an id on the download web server.

and finally, i've updated the gps.html file to match the current namelist
and directory layout.

i've tested this on a couple systems, but as always, if you run into 
anything
strange, please let me know.

have a good weekend,
nancy