wai request modifying functions

[Vlix]

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• Bumped the version number
• Documented new APIs with Haddock markup
• Added @since declarations to the Haddock

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• Update the Changelog.md file with a link to your PR
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Wanted to implement the long-standing #710 PR, and found some parts to also update in documentation and just code cleanup.

[kazu-yamamoto]

Good work.