Pay off the technical debt the project got into during last major refactoring

[oleq]

During the last refactoring (when the project moved to Redux, markers support was implemented, new selection rendering was implemented etc.) a technical debt has piled up. I only had limited time to finish the new features so I decided to ship the new inspector without some code that would normally be there:

• there's no full test code coverage,
• some essential tests are missing (related to the above),
• there's a ton of code without documentation,

This debt is backfiring now when developing new features and fixing bugs. Mostly it's the missing coverage that causes problems because it is so easy to destabilize the application.

[jodator]

The Inspector is used by developers outside the CKEditor team so its stability might impact on how the whole project is perceived. Of course, this is a debug tool so other devs might understand minor bugs as long as the tool is usable.

My POV on this that the sooner we pay off some/most of the dept the better.

[jodator]

Related:

• Remove the Logger class #63 Logger class removal
• Bump acorn from 6.4.0 to 6.4.1 #72 update coverat