bug: obs_window_days and obs_window_seconds are no-ops

🐛

Describe the bug

Somewhere in the translation of the documentation from html to rst, the info about perfect_model_obs and filter ignoring the obs_window_days and obs_window_seconds namelist items got lost. the docs should be updated to say these are not yet functional, and the code should warn the user if they try to use it.

(eventually i think they could be implemented and be useful, but that's a slightly larger task needing a lot of testing.)

it would be quick to at least flag that these aren't implemented yet. the default values of these namelist items are -1. in the filter_mod, in filter_set_window_time(), if the values aren't both -1, it could print a warning or error saying this option is not yet supported. that would at least prevent someone from using them and thinking they were working.

to reproduce, set obs_window_days and obs_window_seconds to something other than -1. nothing changes in which obs are assimilated.

another thing i'd fix - the filter_set_window_time() routine only tests obs_window_days to see if it is >=0. it should also look at obs_window_seconds, i'd think. both default to -1 but someone could leave days as -1 and try only setting seconds. that should be a real error. (same for any time pair of days/seconds.)

i'd be willing to put in code to at least catch this and print a warning or error (your vote here?) if you think that's a good thing to do. let me know?

Error Message

no errors are printed - the settings are silently ignored.

Which model(s) are you working with?

any model.

Screenshots

If applicable, add screenshots to help explain your problem.

Version of DART

Which version of DART are you using?
You can find the version using git describe --tags

Have you modified the DART code?

Yes/No
If your code changes are available on GitHub, please provide the repository.

Build information

Please describe:

1. The machine you are running on (e.g. windows laptop, NCAR supercomputer Cheyenne).
2. The compiler you are using (e.g. gnu, intel).

Start with filter_mod and the filter_set_window_time() routine, then review the documentation translated from HTML to RST for perfect_model_obs and filter. Confirm how obs_window_days and obs_window_seconds are handled, including when only seconds is set. Done means the documentation states the options are unsupported and non-default values produce a warning or error instead of being silently ignored.