Python object input to new Dolo Model constructor

[sbenthall]

Following up on this idea from @llorracc :

When you parse the YAML files, you must be creating some internal python representation of the content of the model. Possibly we could figure out a way to construct those python objects directly, and the result could be swapped back and forth between HARK and Dolo.

The strategy here is to start by generalizing this script from @albop

... and turning it into a new constructor for Dolo models.

Then, circle back and work on ways to integrate HARK models information into the new constructor.