Count: Returns quantity of elements contained by given instance

For example:

ItemCount = Control.Count

Then ItemCount will containg:

- number of controls owned by Control if Control is TWinControl. It is analogue of Delphi's TWinControl.ControlCount property in this case.

- number of items in Control if Control is TStrings. It is analogue of Delphi's TStrings.Count property in this case.

- number of collection items in Control if Control is TCollection. It is analogue of Delphi's TCollection.Count property in this case.