Bug 49117 [Plan Item] Workbench needs hooks for new welcome support
M6 We need to provide an extension point and some interfaces to allow for a primary feature to declare a welcome page. This extension point will be tied the new IProduct being defined by the Core team and needs to have 3 states 1) Fill whole screen 2) Collapsed on the right when the user selects something and starts working 3) Disables when it is no longer of any use
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/IDEWorkbenchAdvisor.java
previousFeatures = new HashSet(Arrays.asList(previousFeaturesArray));
		} else {
			previousFeatures = new HashSet(0);
		}
		
		currentFeatures = computeFeatureSet();
		String[] currentFeaturesArray = new String[currentFeatures.size()];
		currentFeatures.toArray(currentFeaturesArray);
		settings.put(INSTALLED_FEATURES, currentFeaturesArray);
		
		
		newlyAddedFeatures = new TreeSet(currentFeatures);
		newlyAddedFeatures.removeAll(previousFeatures);
		
	}
	/*
	 * Open a welcome editor for the given input
	 */
	private void openWelcomeEditor(IWorkbenchWindow window, WelcomeEditorInput input, String perspectiveId) {
		if (configurer.getWorkbench().getWorkbenchWindowCount() == 0) {
			
			
			return;
		}
	
		IWorkbenchWindow win = window;
		if (perspectiveId != null) {
			try {
				win = configurer.getWorkbench().openWorkbenchWindow(perspectiveId, getDefaultPageInput());
				if (win == null) {