Keep in mind utf8 strings in prefixed hashes

[Lagovas]

Here is merged master into your branch plus fixes with calculating prefixes from utf8 strings instead of encoded arrays. You can review last 2 commits after merge branch or pull changes from master into your branch and refresh.

Checklist

• [ ] Change is covered by automated tests
• [ ] The coding guidelines are followed
• [ ] Public API has proper documentation in the Acra documentation site or has PR on documentation repository with new changes
• [ ] CHANGELOG.md is updated (in case of notable or breaking changes)
• [ ] CHANGELOG_DEV.md is updated
• [ ] Benchmark results are attached (if applicable)
• are up-to-date (in case of API changes)

[Lagovas]

merged into #663