Distributing the corporate income tax across individual taxpayers

[jdebacker]

This PR adds functions to Tax-Brain to distribute the corporate income tax across individual taxpayers.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 86.47959% with 53 lines in your changes are missing coverage. Please review.

Project coverage is 83.13%. Comparing base (82cee97) to head (fa0d3bb).
Report is 3 commits behind head on master.

Files	Patch %	Lines
cs-config/cs_config/helpers.py	35.55%	29 Missing ⚠️
cs-config/cs_config/tables.py	55.00%	9 Missing ⚠️
taxbrain/report_utils.py	68.75%	5 Missing ⚠️
example.py	0.00%	3 Missing ⚠️
cs-config/cs_config/functions.py	71.42%	2 Missing ⚠️
taxbrain/cli.py	80.00%	1 Missing ⚠️
taxbrain/corporate_incidence.py	97.95%	1 Missing ⚠️
taxbrain/tests/conftest.py	66.66%	1 Missing ⚠️
taxbrain/tests/test_brain.py	96.77%	1 Missing ⚠️
taxbrain/utils.py	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #196      +/-   ##
==========================================
+ Coverage   82.00%   83.13%   +1.13%     
==========================================
  Files          21       23       +2     
  Lines        1650     1844     +194     
==========================================
+ Hits         1353     1533     +180     
- Misses        297      311      +14     

Flag	Coverage Δ
unittests	83.13% <86.47%> (+1.13%)	⬆️

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[MaxGhenis]

@kpomerleau fyi