Bug 121498 When datasource/dataset deleted, the datasource/dataset property binding element haven't been deleted
When deleted the datasource/dataset, the datasource/dataset property binding element haven't been deleted. Expected result: This operation must be a transaction.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
* (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.core.DesignElement#getSlot(int)
	 */
	public ContainerSlot getSlot( int slot )
	{
		assert slot >= 0 && slot < getSlotCount( );
		return slots[slot];
	}
	/**
	 * Privates method to create the slots.
	 */
	protected void initSlots( )
	{
		slots = new ContainerSlot[getSlotCount( )];
		for ( int i = 0; i < slots.length; i++ )
			slots[i] = new MultiElementSlot( );
	}
	/**
	 * Records a semantic error during build and similar batch operations. This
	 * implementation is preliminary.
	 * 
	 * @param ex
	 *            the exception to record
	 */
	public void semanticError( SemanticException ex )
	{
		if ( allExceptions == null )
			allExceptions = new ArrayList( );
		allExceptions.add( ex );