Previously, when closing a platform window using the browser close
button, the represented `CPWindow` was not correctly closed.
This patch ensure `-(void)close` is called correctly by using the DOM
`unload` event. Also, delegate method `- (void)windowWillClose:` is
correctly called.
Previously, when calling the method orderOut: on the full platform window of a CPPlatformWindow, cappuccino didn't close the parent CPPlatformWindow. When he does, this only works if the parent platformWindow is not the primary platform.
Test app in Tests/Manual/CPPlatformWindow/