feat: merge_these_atom_params

[diogomart]

Description

Argument to pass parameter keys to merge the corresponding value to the parent atom, when the atoms (hydrogens) are merged. Partial charges are merged by default (the hydrogen charge is added to the parent atom). This allows the user to define additional parameters to be summed to the parent atom.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Checklist:

Please go through the following checklist before submitting the PR:

• Written a description of the feature or bug fix above.
• Ran pytest locally and all tests have passed.
• If applicable, documentation was updated with new feature.
• Docstring included for any new classes/functions/methods, or for significantly modifed existing functions.
• (Optional) new test added to account for new feature.

[atillack]

@diogomart Works well, merging :-)