ERFURT, Germany — A memorial site and educational center to open this week on International Holocaust Remembrance Day documents the role played by a German maker of crematoria in the mass execution of Europe’s Jews and others.Hitler’s top men dreamed up the horrors of the Holocaust, but without the support of German engineers and industrialists like Topf & Sons, they would never have succeeded in murdering millions.Through technology developed and products built in the Topf & Sons factories, Auschwitz was equipped with four crematoria that resembled factories where as many as 8,000 corpses could be burned in a day.