Bug 153896 Improve the performance of BIRT datetime-converting
The current datetime converting algorithm in birt.core, xml&flatfile ODA implementations are not efficient enough.This is because we use java's SimpleDateTimeFormatter to parse ISO8601 compatible date/time values. We should write our own datatime string parser for ISO8601 datetime format.
core/org.eclipse.birt.core/src/org/eclipse/birt/core/data/DataTypeUtil.java
if ( source == null )
			return null;
		if ( source instanceof Date )
		{
			return new Date( ( (Date) source ).getTime( ) );
		}
		else if ( source instanceof String )
		{
			return toDate( (String) source );
		}
		else
		{
			throw new BirtException( pluginId,
					ResourceConstants.CONVERT_FAILS,
					new Object[]{
							source.toString( ), "Date"
					},
					resourceBundle );
		}
	}
    
    /**
     * Date -> Time
     * String -> Time
     * @param source
     * @return
     * @throws BirtException
     */
    public static Time toTime( Object source ) throws BirtException
    {