Bug 189706 Enhance computed column aggregation function handling in UI.
Due to the issue discussed in 189705, current computed column aggregation builder in data set editor has bugs to extend: 1.When new a computed column, the aggregation argument field cannot be correctly set. 2.The argument field cannot be correct grayed out when user select a aggregation function without arguments 3.The available aggregation function list is incomprehensive 4.Some aggregation function cannot be set to model(say, weightedAve).
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/aggregation/AggregationHelper.java
if ( count <= passesNumber )
				{
					validAggregations.add( new Integer( i ) );
					if ( count == passesNumber )
					{
						populateAggrValue[i] = true;
					}
				}
			}
		}
	}
	
	private IAggrInfo getAggrInfo( int i ) throws DataException
	{
		return this.manager.getAggrDefn( i );
	}
	private int getStartingGroupLevel( ) throws DataException
	{
		return this.populator.getResultIterator( ).getStartingGroupLevel( );
		/*return this.populator.getGroupProcessorManager( )
				.getGroupCalculationUtil( )
				.getGroupInformationUtil( )
				.getStartingGroupLevel( );*/
	}
	
	private int getEndingGroupLevel( ) throws DataException
	{
		return this.populator.getResultIterator( ).getEndingGroupLevel( );
		/*	return this.populator.getGroupProcessorManager( )
			.getGroupCalculationUtil( )