Bug 213126 Add support for DataEngine-leve dataset cache
In many cases the DataEngine-leve dataset cache is useful which ensure that a dataset is executed one time during rendering one report. To support this feature a new dataset property should be added. The Birt customer can choose whether this dataset need to be cached or not by setting the property in deisgn time.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DataSetHandle.java
{
					paramName = ( (DataSetParameterHandle) item ).getName( );
				}
				else if ( item instanceof DataSetParameter )
				{
					paramName = ( (DataSetParameter) item ).getName( );
				}
				else
				{
					assert false;
				}
				
				removeParamBindingsFor( paramName );
			}
		}
		/**
		 * Removes the parameter binding for the parameter with the given
		 * parameter name. The parameter binding is defined in clients of the
		 * data set in which this handle exists.
		 * 
		 * @param paramName
		 *            name of the parameter
		 * @throws PropertyValueException
		 *             if error occurs when removing parameter binding.
		 */
		private void removeParamBindingsFor( String paramName )
				throws PropertyValueException
		{
			if ( paramName == null )
				return;