Check usage of context managers

[heuer]

It's a minor issue but several classes provide a context manager where it makes no sense, in my opinion. For example: Where is the use case for a context manager in Output, or CursorManager, or Cursor…?

In my opinion all context managers which have no valid use case should be removed.

[heuer]

OutputLayout is another candidate where the value of a context manager is questionable.

[heuer]

@flacjacket, @jwijenbergh, maybe WLR 0.17 offers a chance to clean this up?

However, I don't think this issue is important enough to delay a release of WLR 0.17.