46 parallelize var inf

[joselotl]

Problem & Solution Description (including issue #)

This commit parallelizes point_est_hist, and var_inf. Also I rewrote naive_stack to share functions with point_est_hist.

Code Quality

• [ ] My code follows the code style of this project
• [ ] I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• [ ] My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• [ ] Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (263b2a6) 96.96% compared to head (382217e) 97.17%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #77 +/- ## ========================================== + Coverage 96.96% 97.17% +0.21% ========================================== Files 32 32 Lines 1714 1736 +22 ========================================== + Hits 1662 1687 +25 + Misses 52 49 -3 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.