A new security decree mandating the preventive detention of potential trouble-makers ahead of demos is not a measure that kills the freedom of assembly, Interior Minister Matteo Piantedosi said after cabinet approved a sweeping package Thursday.     Preventive detention "is not a measure that kills freedom," Piantedosi told a press conference.     "It exists in many jurisdictions, and there is a relationship with the judicial authority, who is informed that the person will be taken to a police