MpdRoot refactoring

• Jan Busa

Room: LHEP-3/221 - Читальный зал библиотеки Discussion on the topic of refactoring until the March release of mpdroot (25.03.25). Early march opening milestone+issues in git with detailed description of changes. Affecting whole code base, it is better to do whole refactoring in one large update rather than to split it in several months as any class renaming will break all classes depending on it.