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
{
	private IAggrDefnManager manager;
	
	private ResultSetPopulator populator;
	
	/**
	 * Array to store all calculated aggregate values. aggrValue[i] is a list of
	 * values calculated for expression #i in the associated aggregate table.
	 * The aggrgate values are stored in each list as the cursor advances for
	 * the associated ODI result set.
	 */
	private List[] currentRoundAggrValue;
	/**
	 * Array to store current argument values to all aggregates argrArgs[i] is
	 * the argument array to aggregate expression #i
	 */
	private Object[][] aggrArgs;
	
	private int currentAggrCount;
	
	private AccumulatorManager[] accumulatorManagers;
	
	private Set invalidAggrSet;
	private Map invalidAggrMsg;
	
	/**
	 * For the given odi resultset, calcaulate the value of aggregate from
	 * aggregateTable