Useless getter in Application class

[LJNeon]

• I have checked issues with bug label and found no duplicates

Unexpected Behavior

Here there's a getter that simply calls return this;. I can't imagine any use cases for this.

Environment

• Typedoc version: GitHub Master

[Gerrit0]

TypeDoc has a "component" architecture, most of the old classes in the project extend the AbstractComponent class.

This class provides a getter - application which is used for any classes in the component hierarchy to access the root level component. Once we get to the Application class though, we don't want to bubble up through the component owners anymore, and just want to return the current object.

Technically, the getter is no longer necessary. Before #845, the AbstractComponent class would return null if the component had no owner and therefore the Application class needed to override the method. Now, there is a check to satisfy strict null checks (with a type assertion that needs to go away eventually).

I want to remove the @Component decorator and the hard to follow component class structure along with it, but this needs to be done in parts to keep the changes small enough that they probably won't break things. (It has already been done to the options + options readers, next up is probably the converters)