Currently when a topic has no xml the <section><title> used is:

No XML Content

Instead, it should use the Topic.Title as the section title. 

It should still include the same note, and it should still appear in Compiler Errors at the end of the book.

Rationale: 

At the moment scanning through the book it is impossible to tell what is supposed to be there. It's ok that there is no content written yet, but we do at least know what is supposed to be there / going to be there, so we should show that. 

As an author previewing my book at the moment, I can't tell what is supposed to go there without referring to the content spec.