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
* 
	 * @param source
	 *            the String to be convert
	 * @param locate
	 * 			  the locate of the string
	 * @return result Date
	 */
	public static Date toDate( String source, Locale locale )
			throws BirtException
	{
		return toDate( source, ULocale.forLocale( locale ) );
	}
	/**
	 * convert String with the specified locale to java.util.Date
	 * 
	 * @param source
	 *            the String to be convert
	 * @param locate
	 * 			  the locate of the string
	 * @return result Date
	 */
	public static Date toDate( String source, ULocale locale )
			throws BirtException
	{
		if ( source == null )
			return null;
		DateFormat dateFormat = null;
		Date resultDate = null;
		
		boolean existTime = source.matches( ".*[0-9]+:[0-9]+:[0-9]+.*" )