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/impl/DataSetCacheUtil.java
* 
	 * @param option
	 * @return
	 */
	private static int getIntValueFromString(Object option) 
	{
		return Integer.valueOf(option.toString()).intValue();
	}
	
	/**
	 * 
	 * @param context
	 * @param appContext
	 * @return 
	 */
	public static int getCacheCount( DataEngineContext context, Map appContext )
	{
		if ( appContext != null )
		{
			Object option = appContext.get( DataEngine.DATA_SET_CACHE_ROW_LIMIT );
			if( option != null )
			{
				return getIntValueFromString(option);
			}
		}
		
		return context.getCacheCount();
	}
}