Cleanup KEditListBox. It looks like this class got totally forgotten...

* Make it working when checkAtEntering is enabled.
* Add two simple new constructor that do not take name and other additional (bool) args.
* Old constructors are still here, but deprecated. Accordng to lxr, there are quite often used. We could drop them, when we can port all calls to the new constructors (which should be quite simple, but would need some help...).
* Cleanup code a bit.

This change is BIC, but should be SC.