ConsPortfolioModel Overhaul

[alanlujan91]

This PR covers a number of changes to ConsPortfolioModel and supporting files:

• Creates object oriented solver to facilitate using pieces of solution method in other solvers.
• Updates solution method for joint distribution of income and risky asset shocks (solver now runs, but there are no proper tests for this feature; an easy test is to assume independent distributions are not independent, which should give very similar if not exactly equal results)
• Sync example notebooks (.py example was outdated with respect to .ipynb)
• Fix example on mathematical limits of model which was outdated

A few comments:

• ConsPortfolioModel does not have enough tests for its different features.
  • Solver on discrete grid
  • Solver on Joint distribution

Please ensure your pull request adheres to the following guidelines:

• Tests for new functionality/models or Tests to reproduce the bug-fix in code.
• Updated documentation of features that add new functionality.
• Update CHANGELOG.md with major/minor changes.

[codecov-commenter]

Codecov Report

Merging #1047 (95c03d3) into master (d59269d) will increase coverage by 1.10%.
The diff coverage is 94.24%.

@@            Coverage Diff             @@
##           master    #1047      +/-   ##
==========================================
+ Coverage   72.53%   73.64%   +1.10%     
==========================================
  Files          68       68              
  Lines       10298    10411     +113     
==========================================
+ Hits         7470     7667     +197     
+ Misses       2828     2744      -84     

Impacted Files	Coverage Δ
HARK/ConsumptionSaving/ConsPortfolioFrameModel.py	100.00% <ø> (ø)
HARK/ConsumptionSaving/ConsPortfolioModel.py	92.15% <93.58%> (+25.86%)	⬆️
...ConsumptionSaving/tests/test_ConsPortfolioModel.py	100.00% <100.00%> (ø)

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[sbenthall]

Just to make a note of my answer to a question you asked earlier ...

The best way to design 'unit tests' is to actually test the functionality of individual units of code, rather than test the output of many components put together (which is technically called an 'integration test').

So, if there are gaps in the test coverage, the best thing to do is drill down and write tests covering the various cases for those specific parts.

[alanlujan91]

Updated and added basic tests for new features. I tried to make sure that it's compatible with Portfolio Frame functionality.

[sbenthall]

Is this ready for review?

Is there a changelog entry for it in the PR?

I wonder if @Mv77 should review this, as he has done a lot of work on the ConsPortfolioModel.

[alanlujan91]

Is this ready for review?

Is there a changelog entry for it in the PR?

I wonder if @Mv77 should review this, as he has done a lot of work on the ConsPortfolioModel.

Yes, this is ready for review.

I would appreciate a review from @Mv77, but also I want to make sure I don't mess up your Portfolio Frame functionality.

I will make some additions to changelog.

[sbenthall]

Ok. I hope that both @Mv77 and I are able to review it.
I'll check for compatibility with my Frame work, hopefully by our regular Thursday meeting.

[sbenthall]

Ok, I have looked over this PR and see how it effects the work on FramedModels.

The changes to the underlying Portfolio model look good to me.

This PR has some merge conflicts with #1064 which seem unavoidable but minor.