Don't steel the mouse/touch events when we must not

E.g. when having a MouseArea and set the preventStealing flag, we do not want the Map item to steel the events.

Change-Id: I9fca66967ef2d9fe9883dabfd5e394026c99d6c9
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Enable wheel mouse wheel for zooming

Change-Id: If80184b81f4e2dcd960be9cf5e70f147fbfa8cf9
Reviewed-by: Anders Gunnarsson <anders.gunnarsson@appello.com>
Reviewed-by: Aaron McCarthy <mccarthy.aaron@gmail.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>