Fixed|libappfw: Memory leak in LogWidget (at shutdown)

The cached entries were not deleted when the widget was deleted.
Fixed|libgui|Font: Memory leak (release font metrics rules)
Fixed|libcore|ArrayExpression: Memory leak

The array expression's arguments were not deleted when the expression
was deleted.
libcore: Cleanup
libappfw|DialogWidget: Specifying a minimum width for a dialog
UI|Client|AlertDialog: Fixed layout problem when dialog is narrow

Now space is reserved for the auto-hide setting.
Fixed|libcore|Scripting: Memory leak in expression evaluator

The scopes for the evaluated results were not always deleted.
Cleanup
Fixed|libappfw|FoldPanelWidget: Memory leak

The content was not deleted if the fold was closed when the widget was
deleted.
Debug|Client: Assert that all reference-counted objects get deleted
Fixed|Client: Memory leak (notification widgets not deleted)

The Alert and Updater notifications were not deleted if they were
hidden when the app was shut down.

Todo: A better ownership model needed for the notification area!
UI|Client|Console: Restored the [>] button appearance
libcore|Widget: Setting a widget's root manually

Normally the root widget is found by tracing all the parents.
libappfw: Added a smart pointer for owning a GuiWidget

Automatically calls the correct destructor on the widget.
libcore|Log: Multithreading robustness

Theoretically, a race condition might occur in theLogs(), if it were
called from multiple threads for the first time.
Cleanup
libcore|Unix|Debug: Macro to generate backtrace as a string
Fixed|libappfw|ChildWidgetOrganizer: Potential memory access issue

Issue found by Guard Malloc. Since we have an iterator already, it
is better to use it to remove the map entry rather than looking it
up again using the key.
Fixed|libappfw|GuiWidgetPrivate: Observe root atlas for deletion

Fixes the problem where the atlas has already been deleted when the
widget is being deleted.
libappfw|GuiWidget: Destroying a GUI widget at a later time

Particularly when handling audience notifications about object deletion,
it is necessary to schedule object deletion later so that potential
pending notifications won't go to deleted objects.