applets/fifteenPuzzle: set minimum size for fullRepresentation
The fullRepresentation does not have a minimum size. This is not a problem in the case of the desktop widget, which will fall back to the compactRepresentation, but it makes no sense for the popup.
Instead, we set it to have a minimum size equal to the switch size. Along the way we get rid of some not particularly useful debug messages.
This makes it impossible to switch a desktop widget to the compact representation. This might be better, though; several other widgets behave like this (e.g. folder view), and the popup from a desktop widget is a somewhat awkward experience.