Qt Quick for .NET: Signal converters

When this task is finished I will be able to:

1. Annotate a C# event as a Qt signal using an appropriate interop attribute;
2. Choose one of the following options:
   1. Provide no further metadata;
      • The event will be mapped to a signal with the same name and an empty parameter list;
      • No conversion between event and signal is required.
   2. Provide a list of signal parameter types;
      • The event properties will be mapped to signal parameters matching the types in the list;
      • An implicit type conversion between event properties and matching signal parameters will be attempted.
   3. Define a custom signal converter class;
      • Override the event argument conversion method;
      • Provide a value for each signal parameter, based on the value of the corresponding event property;
      • Reference the custom signal converter class in the event annotation;
3. When the event is notified, the generated native code will call the associated converter to retrieve the value of each signal parameter;
4. The signal associated to the event is emitted.