Documenting interface of object literals

[mlewand]

We often use object literals, for dialog definitions, CKEDITOR.eventInfo, CKEDITOR.plugins.autocomplete.matchInfo and much, much more.

Typically we put an information like:

This class is not really part of the API. It just illustrates the properties that developers can use to define and create dialogs.

Which is petty readable, but we repeat it in many different places. But we need a common way to do that, preferably just to mark the type with a single tag like @interface or @virtual. That should cause Umberto to include a proper information box.

I'm just wondering about semantically best tag. We can eventually try to extend JSDuck with our own.

I believe best fit would be @interface tag, altough we need to clearly mark that it does not exists in namespaces.

[f1ames]

Moved to ckeditor/ckeditor4#2896.