chore: improve code readability and style in regressions.py and splitSources.py

[Pronoss]

• Updated docstrings and comments for clarity and grammatical correctness.
• Fixed phrasing: "sources into their own files" → "sources into separate files".
• Improved uncaught exception handling print formatting in splitSources.py.
• Replaced manual string slicing with startswith() for better readability and Python best practices.
• Standardized class naming: regressor → Regressor.
• Improved comment wording for non-ASCII handling.
• Minor whitespace and indentation adjustments.

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[Pronoss]

Hi @solidity – just a friendly reminder about PR #15959 (“chore: improve code readability and style in regressions.py and splitSources.py”). It updates docstrings, switches string slicing to startswith(), standardizes the Regressor class name, and refines exception handling in splitSources.py. When you get a moment, could you take a look? Thanks! 🚀

[Pronoss]

Thank you, @clonker, for catching and fixing that typo! Everything looks good to me now.

[clonker]

Could you please squash into one or two commits and rebase? We don't want to have merge commits on develop.

[Pronoss]

Hi @clonker,

I’ve squashed all changes into a single commit and rebased onto develop as requested. Let me know if there’s anything else to adjust—thanks!