Add factory module for extra misfit terms

[keurfonluu]

• Added: a new submodule evodcinv.factory to group commonly used extra misfit terms (e.g., regularization) (see #15).
• Changed: no longer normalize misfit. This change is to get a "physical" meaning out of RMSE misfit when there are no input uncertainties (e.g., RMSE can be interpreted as average misfit in km/s when inverting dispersion curves). This change should slightly affect previous simulations (i.e., with the same seed).

Reminders:

• [x] Run invoke format to make sure the code follows the style guide,
• [x] Add tests for new features or tests that would have caught the bug that you're fixing,
• [x] Write detailed docstrings for all functions, classes and/or methods,
• [x] If adding new functionality, unit test it and add it to the documentation.

[codecov[bot]]

Codecov Report

Patch coverage: 51.72% and project coverage change: -0.33% :warning:

Comparison is base (a290e72) 53.03% compared to head (e490fe2) 52.70%. Report is 6 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #17 +/- ## ========================================== - Coverage 53.03% 52.70% -0.33% ========================================== Files 17 19 +2 Lines 643 666 +23 ========================================== + Hits 341 351 +10 - Misses 302 315 +13 ``` | [Files Changed](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu) | Coverage Δ | | |---|---|---| | [evodcinv/\_progress.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvX3Byb2dyZXNzLnB5) | `100.00% <ø> (ø)` | | | [evodcinv/\_result.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvX3Jlc3VsdC5weQ==) | `20.10% <0.00%> (-0.11%)` | :arrow_down: | | [tests/test\_model.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-dGVzdHMvdGVzdF9tb2RlbC5weQ==) | `100.00% <ø> (ø)` | | | [evodcinv/factory/\_extra\_terms.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvZmFjdG9yeS9fZXh0cmFfdGVybXMucHk=) | `38.88% <38.88%> (ø)` | | | [evodcinv/\_curve.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvX2N1cnZlLnB5) | `56.33% <50.00%> (-0.19%)` | :arrow_down: | | [evodcinv/\_\_init\_\_.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvX19pbml0X18ucHk=) | `100.00% <100.00%> (ø)` | | | [evodcinv/\_model.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvX21vZGVsLnB5) | `74.25% <100.00%> (-0.13%)` | :arrow_down: | | [evodcinv/factory/\_\_init\_\_.py](https://app.codecov.io/gh/keurfonluu/evodcinv/pull/17?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Keurfon+Luu#diff-ZXZvZGNpbnYvZmFjdG9yeS9fX2luaXRfXy5weQ==) | `100.00% <100.00%> (ø)` | |

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