Remove UserSettings From Engine

[CharliePoole]

In TestCentric/testcentric-gui#580 we agreed that both projects would drop user settings from their engines for compatibility. Handling settings is application-specific. This change is breaking.

[CharliePoole]

This is ready to work on but we need to decide how to handle user settings. In the GUI, I handled them by continuing to use the same XML settings file, moving the code out of the engine to the GUI Model. We could do something similar here or we could use a different approach for saving settings. @ChrisMaddock What do you think?

[ChrisMaddock]

What do we actually save in the settings? I thought it was unused.

[CharliePoole]

It's only used indirectly in the console runner - by the RecentFilesService. So I guess RecentFiles is what really needs to be replaced. I would lean towards placing it by somethings simple, preferably by a standard approach used by other apps. Once that's done, then there's no more use of UserSettings.

[ChrisMaddock]

What does the console do with RecentFilesService?

I guess it depends on the use-case how we replace it - but I can't particularly think what it would be needed for...

[CharliePoole]

Turns out I was wrong... UserSettings and RecentFiles both are only used by their tests.

[CharliePoole]

Blocked by #896

[CharliePoole]

This was merged to dev-4.0 and closed. I'm reopening it so as to replicate it in main.