This is only done if we are runing the updater or package
manager. As of before, the widgets where hidden and shown
again wich feels a bit strange as we never leave the page,
but it seemed so.
Introduce some magic marker to differentiate between update and
package management modus. The base installer now needs explicite
arguments passed to make the app an updater or package manager.
Adjustment some more classes to take the new markers into account.
The wizard page should not allow to specify an empty installation
path. Hence reject the wizard to proceed
Reviewed-by: Niels Weber
Task-number: QTSDK-540
