- Change wrong player permissions to admin permissions
- Rename command class names that were the same for the ordinary vs. admin task
- Create test to ensure that commands with OP_ONLY default require an admin permission node
- Reduce tight coupling by passing list of available commands as param to CommandHandler
- Split command processing method into several smaller ones
- Remove unfinished logic for unlimited command arguments (reason: was not implemented and not used, probably needs another way to handle it once the need for it arises)
- Create test for CommandHandler
- Create builder class for CommandDescription
- Remove redundant methods in command registration classes (e.g. certain validation is superfluous because we only instantiate the classes internally)
- Replace multiple occurrences where a field is directly instantiated e.g. with a list and then its value is overwritten by a constructor = redundant instantiation of objects
