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/impl/ComputedColumnHelper.java
if ( ExpressionCompilerUtil.hasAggregationInExpr( column.getExpression( ) ) )
				{
					continue;
				}
				else
				{
					List referedList = ExpressionUtil.extractColumnExpressions( ( (IScriptExpression) column.getExpression( ) ).getText( ) );
					if ( referedList.size( ) == 0 )
					{
						result.add( column );
					}
					else
					{
						List newList = new ArrayList( );
						for ( int j = 0; j < referedList.size( ); j++ )
						{
							IColumnBinding binding = (IColumnBinding) referedList.get( j );
							String name = binding.getResultSetColumnName( );
							newList.add( name );
						}
						if ( !hasAggregation( newList, dataSetCCList ) )
						{
							result.add( column );
						}
					}
				}
			}
		}
		catch ( BirtException e )
		{