Refactor CreateNewTracker to improve efficiency when loading data from DB

[Issung]

In GChan/Utils.cs CreateNewTracker(LoadedData data) a tracker is made by creating one from the url from the db, then setting the properties one by one, this looks nasty and will also be spamming NotifyPropertyChanged events one by one to the UI. This will be impacting startup time greatly when the user has a lot of threads saved.

There is a TODO in the code:

// TODO: Should be making trackers based on the LoadedData (pass loadeddata to constructor).
// Rather than making them and then loading them with more data.
// This would help app-startup ui responsiveness as it would reduce the notify property changed spam greatly.

Will require some refactoring of how trackers get made, not much.

• Make LoadedData (the base class) abstract.
• Check the type of the loaded data in CreateNewTracker to see if its thread or board.
• Maybe need a overload for each case that makes a thread/board tracker without checking if its a thread or board.
• Pass the loaded data into the constructor of the thread/board.
• Set the properties instantly in the constructor instead of one by one outside the ctor.
• Clean up remaining code/comments.