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
{
			acc = accumulatorManagers[aggrIndex].getCurrentAccumulator( );
		}	
		
		
		boolean accepted = true;
		if ( aggrInfo.getFilter( ) != null )
		{
			try
			{
				Object filterResult = ExprEvaluateUtil.evaluateValue( aggrInfo.getFilter( ),
						this.populator.getCache( ).getCurrentIndex( ),
						this.populator.getCache( ).getCurrentResult( ),
						this.populator.getQuery( ).getExprProcessor( ).getScope( ) );
				if ( filterResult == null )
					accepted = true;
				else
					accepted = DataTypeUtil.toBoolean( filterResult )
							.booleanValue( );
			}
			catch ( BirtException e )
			{
				if ( invalidAggrMsg == null )
					invalidAggrMsg = new HashMap( );
				invalidAggrMsg.put( new Integer( aggrIndex ), e );
				return false;
			}
		}
		if( aggrInfo.getCalcualteLevel( ) > 0 )
		{