Check commented code, TODOs, and FIXMEs in the codebase

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In the early days of the bindings, it was common to comment code out as a quick and dirty way to disable them. Some of them remained to this day, still broken in their original shape, and outdated compared to the rest of the codebase. TODOs and FIXMEs without issue numbers were also common. Some of these are already done, some others are not. We should look for them in the codebase and:

• If a section of commented code is no longer relevant, remove it.
• If a section of commented code is relevant, uncomment and fix it if possible. Otherwise, remove it and create an issue.
• If a TODO or a FIXME is done or otherwise no longer applicable, just remove them. Otherwise, remove them and create an issue.
• Establish that future TODO or FIXME comments must be accompanied with a GitHub issue number.