Parameterize the limitation on capital losses

[jdebacker]

This PR addresses Issue #2632 by parameterizing the capital loss limitation.

[codecov]

Codecov Report

Merging #2707 (bf6332a) into master (6798fba) will not change coverage.
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Additional details and impacted files

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Flag	Coverage Δ
unittests	98.54% <ø> (ø)

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Files	Coverage Δ
taxcalc/utils.py	97.79% <ø> (ø)

[jdebacker]

@MattHJensen This PR is ready for your review. Thanks!

[MattHJensen]

@jdebacker, do you think we should protect puf and cps users from setting this parameter outside of the ranges supported by their data? Or say this param isn't compatible with those data?

[jdebacker]

@MattHJensen Good point about data limitations affecting this parameter's usefulness. To address this concern, I've added a note about this in the "notes" metadata field for the capital_loss_limitation parameter.

Note that I am reluctant to set "puf": false in the compatible_data field because the parameter will work with the PUF as expected, so long as the values is less than or equal to the current law value (as the PUF does not provide information on capital losses beyond the current law limit).

Do you think this is satisfactory?

[jdebacker]

@MattHJensen I think this PR is ready to merge. Let me know if you have further thoughts. Will merge if I don't hear back in about 24hrs. Thanks!