Provides project based content manager implementation.

Project content source manager is capable of retrieving all contents inside a project.

Usage:

    	// direct invocation
    	IProject project = xxx;
    	IContentSourceManager manager = new ProjectContentSourceManager(project);
    	List<IContent> contents = manager.getRootContents(IContent.TYPE_S60_ALL);

    	// or via the project design nature
    	manager = S60DesignProjectNature.getUIDesignData(project);