Everything internal

[unitystevem]

Description

Make as much of the Project Auditor API as possible be internal. For everything which is still public, add formatted comments to aid autogenerated API documentation.

Checklist

Before review:

• [x] Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
• [ ] Tests added/changed, if applicable.
  • Functional tests Area_CanDoX, Area_CanDoX_EvenIfYIsTheCase, Area_WhenIDoX_AndYHappens_ThisIsTheResult.
• [x] Docs for new/changed API's.
  • Code is annotated using Xmldoc syntax.

[unitystevem]

Bypassing branch protections because Marco is on PTO (but he approved these changes in principle before he went, and Boris has reviewed them)