Bug 124067 When select the XML file, the relative path should be supported.
Description: When select the XML file, the relative path should be supported. Step to reproduce: 1. new a report 2. new a datasource and dataset based on a XML file 3. select the XML file, the file relative path should be used. Actual result: only the absolute path is supported. Expect result: the relative and absolute path are supported.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/adapter/ModelDteApiAdapter.java
* @throws EngineException
	 */
	IComputedColumn newComputedColumn( ComputedColumnHandle modelCmptdColumn )
			throws EngineException
	{
		
		if ( modelCmptdColumn.getExpression( ) == null )
		{
			throw new EngineException(
					MessageConstants.MISSING_COMPUTED_COLUMN_EXPRESSION_EXCEPTION,
					modelCmptdColumn.getName( ) );
		}
		return new ComputedColumn( modelCmptdColumn.getName( ),
				modelCmptdColumn.getExpression( ),
				toDteDataType( modelCmptdColumn.getDataType( ) ) );
	}
	/**
	 * Creates a new DtE API IJSExprFilter or IColumnFilter from a model's
	 * filter condition. Could return null if no expression nor column operator
	 * is defined.
	 */
	IFilterDefinition newFilter( FilterConditionHandle modelFilter )
	{
		String filterExpr = modelFilter.getExpr( );
		if ( filterExpr == null || filterExpr.length( ) == 0 )
			return null; 
		
		String filterOpr = modelFilter.getOperator( );
		if ( filterOpr == null || filterOpr.length( ) == 0 )
			return new FilterDefinition( new ScriptExpression( filterExpr ) );