By John Crewdson, Tribune senior correspondent. Reporting and research assistance was provided by Drew Crosby in Madrid MADRID -- The most sweeping criminal indictment to arise thus far from the Sept. 11 attacks reflects a quiet but dramatic change in understanding by investigators here and across Europe of the terrorist organization known as Al Qaeda, and the international Islamic radical-terrorist network of which, they now agree, it is merely a part. As laid out in the indictment, the defendants' alleged activities--from arranging travel and providing introductions to procuring false documents and, especially, moving money--provide the first detailed look at one...