Only list necessary parameters in .settings files

[forsyth2]

Currently, parameters defined high up in the inheritance hierarchy will show up in .settings files for tasks they aren't used in. For instance, www is often defined in [default] but [ts] doesn't actually use www. This isn't a huge problem but it can confuse users and developers.

[forsyth2]

Started looking into this as part of #204, but it is a bit tedious.

In zppy/utils.py:

# -----------------------------------------------------------------------------                                                                                          
# Condense directory to only have necessary settings                                                                                                                     
# To find all used parameters, run:                                                                                                                                      
# `git grep "c\[" zppy/<task.py` and `git grep "{{" zppy/templates/<task>.bash`                                                                                          

def condense_settings(settings_dict, used_parameters):
    keys = list(settings_dict.keys())
    used_parameters = set(used_parameters)
    slurm_header_parameters = ["nodes", "partition", "prefix", "qos", "scriptDir", "walltime"]
    used_parameters = used_parameters.union(slurm_header_parameters)
    for key in keys:
        if key not in used_parameters:
            settings_dict.pop(key)
    return settings_dict

In zppy/tc_analysis.py, for instance, the following would be added

            used_parameters = ["atm_name", "case", "debug", "dry_run", "environment_commands", "input_subdir", "input_files", "output", "prefix", "scratch", "scriptDir", "year1", "year2", "years"]
            c = condense_settings(c, used_parameters)

above these lines:

            # Create script                                                                                                                                              
            with open(scriptFile, "w") as f:
                f.write(template.render(**c))

            with open(settingsFile, "w") as sf:
                p = pprint.PrettyPrinter(indent=2, stream=sf)
                p.pprint(c)
                p.pprint(s)

Would also need to account for parameters in zppy/__main__.py.