HSV function estimates (age specific, each line representing a different age)

ETRs

MTR, labor income

MTR, capital income

Codecov Report

Attention: Patch coverage is 30.76923% with 54 lines in your changes missing coverage. Please review.

Project coverage is 72.44%. Comparing base (0261fbf) to head (3da5b4a).

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- Coverage   72.76%   72.44%   -0.32%     
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  Files          19       19              
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+ Hits         3379     3402      +23     
- Misses       1265     1294      +29     

Currently tests pass on Mac OS, fail on Linux (not yet run on Windows). Test failure is with the SSE from the regressions for the HSV functions. These are computed via simple matrix operations and thus I'm surprised there is any difference across platforms. @rickecon Any ideas why dot products would not be identical across platforms?

@rickecon This PR is ready for your review.

The changes to starting values (which apply to the GS and DEP functions only) are to estimate the specified tax functions for all ages via a global optimizer (in this case, scipy.optimize.differential_evolution), then use these parameter estimates for the initial guess for the first age group. Following that, the parameter estimates for each age are used as starting values for the next age.

@jdebacker. The Linux/Python 3.10 test seems to be stalled out. I wonder what is going on with the tests. I am just waiting for these all to pass. I approved all the code changes.

@jdebacker. This looks great and all checks have passed. Merging.