Fixed a tiny typo which prevented compilation
New Fixes

-If the card has its face down it does not respond neither to the
pressed() nor the move() thus nor the release() method.

-Make the CardLabel widget emit signals on every mouse event

-Added a property to CardLabel to tell if it's on top of the pile or
not.

-Deleted the no useless showCard() method in MWindow
Merge branch 'master' of https://github.com/jcespinoza/SolitarioTDA2