Add case_study object

[jklenzing]

Is your feature request related to a problem? Please describe.
It would be nice if there was an object that could duplicate a given run. Could potentially be used as a community database for published output of sami2py.

Describe the solution you'd like
Need to create a case_study object with some level of hierarchy for storing multiple run types under a given topic. A mechanism should exist for to allow a user to duplicate a run from a published paper and tweak parameters after this. Essentially you should be able to use the case_study parameters as the default in run_model and adjust from there.

[jklenzing]

Could this just run from the metadata?

[jklenzing]

Plan:

• Finish and merge STY: revisit keywords #150
• Create new object in class that houses the info dict
• Class has function to read/write to netcdf as metadata
• run_model invokes this class to prepare the model, then calls hidden _run_model_from_info which is existing write namelist and run executable
• New class has pass-thru function that calls new hidden run model code