config and cleanups

- ADD: JsonFileConfigRepository
- FIX: saving INI file
- CHG: code cleanups
loggers

- ADD: Create() methods for FallbackLogger, AggregateLogger and
DelegateLogger
- CHG: if all loggers/handlers of AggregateLogger and DelegateLogger
failes, an exception is thrown
- CHG: code cleanups and improvements
ReceiveNotificationFromAttribute

- CHG: SenderName of ReceiveNotificationFromAttribute cannot be empty
anymore
improved SynchronizedObservableCollection<T> class
collections, cleanups and cleanups

- ADD: DispatcherObservableCollection that uses a Dispatcher for each
operation
- ADD: AddRange() method to SynchronizedObservableCollection<T>
- FIX: AddRange() helper / extension method
- CHG: code cleanups and improvements
code cleanups