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.start();
			newGroup = true;
			/*for ( int i = 0; i < aggrInfo.getArgument( ).length; i++ )
			{
				
				
				
				
				if ( argDefs.length <= i )
				{
					throw new DataException("InvalidAggregtionExpression");
				}
				if ( !argDefs[i] )
				{
					IBaseExpression argExpr = aggrInfo.getArgument( )[i];
					try
					{
						aggrArgs[aggrIndex][i] = ExprEvaluateUtil.evaluateValue( argExpr,
								this.populator.getCache( ).getCurrentIndex( ),
								this.populator.getCache( ).getCurrentResult( ),
								this.populator.getQuery( ).getExprProcessor( ).getScope( ) );
					}
					catch ( BirtException e )
					{
						throw DataException.wrap( e );
					}
				}
			}*/
		}
		else