multi_model_analysis command

[tylerbarna]

This is a command line function that will allow for users to provide multiple models/priors so they can all be run for one lightcurve at the same time and then directly compared against one another at the time of analysis. This is distinct from the existing functionality of light_curve_analysis and providing multiple models; the existing light_curve_analysis code allows for one to use a combination of multiple models to perform one analysis on a lightcurve (eg fitting a lightcurve to a mix of Model A and Model B, effectively Model A/B). This script would perform individual analysis of the lightcurve for each provided model and then compare the analyses against one another.

No actual functional code as of yet, but the scaffolding for a multi_model_analysis function has been created. There's a bunch of comments in the new file regarding implementation.

resolves #214

[bfhealy]

@tylerbarna This framework looks on the right track to facilitate multi-model analyses. Perhaps a good next step is to adapt your settings.json file in nmma-rapid to a config file in YAML format, as mentioned in today's meeting? Then YAML-parsing code could be added here to read all arguments.

It might be additionally helpful to add a script to generate a YAML file automatically. It could call analysis.py get_parser to get its arguments/defaults, ensuring that your YAML file has the latest inputs. After that, you could modify the YAML manually as desired before running multi_model_analysis.py.