Adds a command handler. Dialogue will pause execution after the command is called.
public void AddCommandHandler(string commandName, Delegate handler);
When this command handler has been added, it can be called from your Yarn scripts like so:
<<commandName param1 param2>>
handleris a method that returns an
System.Collections.IEnumerator, when the command is run, the DialogueRunner will start a coroutine using that method and wait for that coroutine to stop before delivering any more content.