Bug 152828 Add the projectFolder property on module
When user doesn't set the resource folder path in designer, there should be a default working path for Birt to manage the report design and find the related resources. A new property should be added on Module: name: projectFolder type:URL This property only can be given from the open design method from session but should not be set after the module initialized. Concern about the backward compatiblity issue, a new method will be added. Open design with a config argument.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
*            The id of the element to find.
	 * @return The element itself, or null if the element can't be found or if
	 *         IDs are not enabled.
	 */
	public DesignElement getElementByID( long id )
	{
		if ( idMap == null )
			return null;
		return (DesignElement) idMap.get( new Long( id ) );
	}
	/**
	 * Returns the undo/redo stack for this module.
	 * 
	 * @return The "command" stack.
	 */
	public ActivityStack getActivityStack( )
	{
		return activityStack;
	}
	/**
	 * Preprares to save this module. Sets the modification date.
	 */
	public void prepareToSave( )
	{
	}
	/**
	 * Records a successful save.
	 */
	public void onSave( )
	{