Make non-Latin1 languages work in documentation and language files

[numeredev]

DESCRIPTION

Is your change request related to a problem? Please describe.
Non-Latin1 languages like Chinese do not work with the internal CP1252. We've to find another solution to keep the encoding clear.

Describe the solution you'd like
Change the internal encoding to enable Non-Latin1 encodings. Possible candidates are std::wstring with wide-char conversion or std::u8string if supported by the compiler.

Describe possible alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered, if any.

Additional context
https://github.com/orgs/numere-org/discussions/102#discussioncomment-7934051

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DEVS' SECTION

ANALYSIS

(Describe, what's the issue and which changes have to be made)

IMPLEMENTATION STEPS

(see also our Wiki for implementation guidelines)

• Implement the necessary changes in a new branch created here on GitHub
• Test your implementation

DOCUMENTATION STEPS

(see also our Wiki for further information)

• Update the changes log
• Add comments to your implementation
• Add Doxygen documentation comments
• Create or update the documentation articles (*.NHLP and *.NDB files, if needed)
• Update the language strings (*.NLNG files, if needed)

PULL REQUEST

• Create a pull request for your changes
• Fill out the template
• Assign @numere-org/maintainers as reviewers