Pretty print for the model class

Goal

We need to have a nice printout of the model class. Users should be able to quickly inspect what the model is without having to list all members of the model class.

Context

During the development of the tutorials, it became apparent the need for this feature.

Required features

• It should have the __str__() method (see this).
• It should print something like the following:

pyrenew.[Model instance]
Number of parameters: [a number goes here]
State of the MCMC: [run/not run]
Model components:
- [Latent process 1]
- [Latent process 2]
- [...]
First (k) parameters: param1, param2, ..., (omitting [N - k]).

Model components can be sort of an instance-dependent print implemented in a hidden function, e.g., _print_details().

Specifications

• __str__() method for the Model metaclass.
• _print_details() method for the Model instances.
• Update the tutorials to include the model prints.
• Add a test that check for the required cases (TBD).

No file or test is named, so start by locating the Model metaclass and its model instance classes, then inspect the tutorials that demonstrated the need for this output. Define the required string sections, instance details, parameter truncation, and MCMC state, update tutorial usage, and add tests covering the listed cases.