Realm-dotnet: RealmObject to notify when removed from realm

[tom-pratt]

Goals

Be able to observe when an individual RealmObject is removed from the realm.

e.g. the RealmObject's IsValid property is included in INotifyPropertyChanged events. Or another similar mechanism.

Currently in situations where updates occur in the background that could delete a RealmObject it feels like you have to check IsValid before every use of the object.

[nirinchev]

That's a good idea - I'll add it to our backlog and we'll look into it in the near future.