Bug 152443 Support boolean type in data set
Support boolean type in data set. It'll cause some data transform issue with absence of boolean type.
core/org.eclipse.birt.core/src/org/eclipse/birt/core/data/DataTypeUtil.java
* @return
	 * @throws BirtException
	 */
	public static Boolean toBoolean( Object source ) throws BirtException
	{
		if ( source == null )
			return null;
		if ( source instanceof Boolean )
		{
			return (Boolean) source;
		}
		else if ( source instanceof Number )
		{
			
			if ( ( (Number) source ).doubleValue( ) == 0 )
				return new Boolean( false );
			return new Boolean( true );
		}
		else if ( source instanceof String )
		{
			if ( ( (String) source ).equalsIgnoreCase( "true" ) )
				return Boolean.TRUE;
			else if ( ( (String) source ).equalsIgnoreCase( "false" ) )
				return Boolean.FALSE;
			else
			{
				try
				{
					if ( Integer.parseInt( (String) source ) == 0 )
						return Boolean.FALSE;