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- Restrict "RegisterClasses" option in unit configs to class overrides only [5.3.0-B1]
- Disallow usage of undefined class properties [5.2.1]
- Move out classes from /core/kernel/utility/cache.php file [5.3.0-B1]
- Group files into folders under /core/kernel folder [5.3.0-B1]
- Check for JSON support during installation [5.2.1]
- ...