Now unloadable: Services and PreferenceBrowser

Hi -

With the latest updates both Services and PreferenceBrowser should now
be un- and reloadable. To unload Services (which depends on
PreferenceBrowser and consequently needs to be unloaded first) execute:

        SystemChangeNotifier uniqueInstance
                noMoreNotificationsFor: ServiceRegistry.
        (MCPackage named: 'Services-Base') unload.

and to unload PB:

        (MCPackage named: 'PreferenceBrowser') unload.
        "Clean out various obsolete references"
        TheWorldMainDockingBar updateInstances.
        TheWorldMenu removeObsolete.
        Flaps disableGlobalFlaps: false.
        Flaps enableGlobalFlaps

To load them back in simply load the packages (PB first, then
Services-Base) from source.squeak.org:

        (Installer repository: 'http://source.squeak.org/trunk')
                install: 'PreferenceBrowser';
                install: 'Services-Base'.
        TheWorldMainDockingBar updateInstances.
        Flaps disableGlobalFlaps: false.
        Flaps enableGlobalFlaps

Have people tried unloading other packages? I'd like to start assembling
the scripts in one place so that we can track our progress. Ultimately,
I'd like to have a script which unloads everything we know how to
unload, ensures that no Undeclared or obsolete behaviors remain, run the
remaining test cases, then reload the packages again, and rerun the
tests. If we can do this consistently we should know quite well how
close we are towards a kernel image.

Cheers,
   - Andreas