Improve string parsing in reaction.delta method

[NilsHeunemann]

Previously the reaction.delta method would return the potential energy of the transition state when supplying "G ddagger" or "G double dagger". This behavior was unexpected.

After the change synonyms "ddagger" and "double dagger" can also be used with free energy.

• Improved string parsing that all synonyms for double dagger can be used
• Added tests that determine if right energy is returned

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Checklist

• [x] The changes include an associated explanation of how/why
• [x] Test pass
• [x] Documentation has been updated
• [x] Changelog has been updated

[t-young31]

Hi @NilsHeunemann – this is awesome, thanks. Would you mind:

• [ ] Updating the changelog
• [ ] Add yourself to the contributors list

Then I'm very happy to approve and merge this 🚀

[codecov[bot]]

Codecov Report

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

Project coverage is 97.44%. Comparing base (67ed012) to head (475764c).

:exclamation: Current head 475764c differs from pull request most recent head 47f262c. Consider uploading reports for the commit 47f262c to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## v1.4.3 #325 +/- ## ======================================= Coverage 97.44% 97.44% ======================================= Files 209 209 Lines 23747 23761 +14 ======================================= + Hits 23141 23155 +14 Misses 606 606 ``` | [Flag](https://app.codecov.io/gh/duartegroup/autodE/pull/325/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=duartegroup) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/duartegroup/autodE/pull/325/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=duartegroup) | `97.44% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=duartegroup#carryforward-flags-in-the-pull-request-comment) to find out more.

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[NilsHeunemann]

Hi, thank you for the quick reply! I just updated the changelog and added myself to the contributors list.