Pavementing the way into 0.2.0

[fedebenelli]

The most important additions are:

• $G^E$ models fundamental objects, and Tapenade API
• NRTL Tapenade implementation
• Saturation points

Still todo to close this:

• [ ] Fully working UNIFAC
• [x] Rest of saturation points
• [x] Tests to reach coverage

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.46164% with 113 lines in your changes are missing coverage. Please review.

:exclamation: No coverage uploaded for pull request base (main@7c5243f). Click here to learn what that means.

Files	Patch %	Lines
.../models/excess_gibbs/group_contribution/unifac.f90	80.68%	20 Missing and 8 partials :warning:
src/adiff/autodiff_api/tapenade_ar_api.f90	76.11%	3 Missing and 13 partials :warning:
...sistency/consistency_tests/consistency_armodel.f90	79.48%	0 Missing and 16 partials :warning:
src/adiff/autodiff_api/tapenade_ge_api.f90	72.00%	7 Missing and 7 partials :warning:
src/phase_equilibria/flash.f90	83.33%	7 Missing and 3 partials :warning:
src/phase_equilibria/saturations_points.f90	86.20%	5 Missing and 3 partials :warning:
src/math/continuation.f90	84.84%	3 Missing and 2 partials :warning:
src/thermoprops.f90	94.89%	3 Missing and 2 partials :warning:
test/fixtures/adiff_pr76.f90	84.21%	3 Missing :warning:
..._helmholtz/cubic/mixing_rules/quadratic_mixing.f90	97.26%	1 Missing and 1 partial :warning:
... and 6 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #49 +/- ## ======================================= Coverage ? 90.97% ======================================= Files ? 41 Lines ? 1729 Branches ? 134 ======================================= Hits ? 1573 Misses ? 87 Partials ? 69 ```

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[fedebenelli]

UNIFAC is still a WIP, but maybe with all the new changes we are ready for v0.2? UNIFAC can be left to v0.3 IMO