Bug 180842 Config memory buffer size in data engine execution.
To tuning the performance, it is necessary for DtE to expose API for clients to config the size of memory it used to store the final result set. A new AppContext string, "org.eclipse.birt.data.cache.memory.size" is proposed. The new appcontext entry only accept positive integer as input, the unit of which would be MB.
data/org.eclipse.birt.data.tests/test/org/eclipse/birt/data/engine/api/APITestCase.java
{
	
	protected String DriverClass;
	protected String URL;
	protected String User;
	protected String Password;
	
	private String tableName;
	protected TestDataSource dataSourceInstance;
	
	
	protected DataEngine dataEngine;	
	/**
	 * Every test case might have one datasource and dataset. They are defined
	 * in base class for convinience to use.
	 */
	protected BaseDataSourceDesign dataSource;
	protected BaseDataSetDesign dataSet;
	
	/*
	 * @see TestCase#setUp()
	 */
	protected void setUp( ) throws Exception
	{
		super.setUp( );