Add 2x new fonts & use them in the user-interface.
Implement C++ model (QAbstractTableModel).

- using the CollectionItem delegate for saving properties
  such as title, artist, album is bad. the delegate is
  managed by the ListView and may not be initialized or
  already deleted. we have to access the model for that.
- the C++ CollectionModel provide basic model/view capabilities.
  it handles role-names (Qml required) and provides an
  invockable (by Qml) get() method.