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
}
					catch ( BirtException e )
					{
						if ( resultClass.wasAnyType( columnIndexArray[i] ) )
							throw new DataException( ResourceConstants.POSSIBLE_MIXED_DATA_TYPE_IN_COLUMN );
						
						String fieldName = resultClass.getFieldName( columnIndexArray[i] );
						if ( fieldName != null
								&& fieldName.startsWith( "_{$TEMP_" ) )
						{
							
							throw new DataException( ResourceConstants.WRONG_DATA_TYPE_SCRIPT_RESULT,
									new Object[]{
											resultClass.getFieldValueClass( columnIndexArray[i] )
													.getName( ),
											value == null ? value
													: value.toString( ),
									} );
						}
						
						throw new DataException( ResourceConstants.WRONG_DATA_TYPE_COMPUTED_COLUMN,
								new Object[]{
										resultClass.getFieldName( columnIndexArray[i] ),
										resultClass.getFieldValueClass( columnIndexArray[i] )
												.getName( ),
										value == null ? value
												: value.toString( ),
								} );
					}
					resultObject.setCustomFieldValue( columnIndexArray[i],