Fix V and V Result tab and Model Checking preferences settings

There are a couple of small fixes to do:

• in the V and V Results view, when right-clicking on a check and selecting Show result, nothing happens. The correct behavior is to open the relative view;
• in the Model Checking tab of Preferences, when a path of a local tool is set, it will not be stored unless the Apply button is clicked. The path should be stored also when clicking Apply and Close.
• Another fix needed is the timeout setting. It is not stored when the dialog is closed.