Bug 180189 Support in memory data set cache.
Currently, Design-Time Data Cache is stored on disks. By performance tests using ramdisk, we found that caching in physical memory can improve the performance of RunAndRender by 30%.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/api/DataEngine.java
* @return an instance of DataEngine under specified context
	 */
    public static DataEngine newDataEngine( DataEngineContext context )
    {
    	try
		{
			return newDataEngine( null, context );
		}
		catch ( BirtException e )
		{
			
			throw new RuntimeException( e );
		}
    }
    
    /**
     * @param context
     * @return
     * @throws BirtException 
     */
    public static DataEngine newDataEngine( PlatformConfig platformConfig,
			DataEngineContext dataContext ) throws BirtException
	{
		Platform.startup( platformConfig );
		Object factory = Platform.createFactoryObject( IDataEngineFactory.EXTENSION_DATA_ENGINE_FACTORY );
		if ( factory instanceof IDataEngineFactory )
		{
			return ( (IDataEngineFactory) factory ).createDataEngine( dataContext );
		}
		else