A mass deployment of police to Polish schools has helped calm tensions, Prime Minister Donald Tusk said on Monday, after three stabbing attacks in four days sparked ?fears of copycat violence. Authorities have dismissed rumours that the attacks were linked to an online challenge or organised group. However, the government says the glorification of violence online is harming young people and it is fast-tracking legislation to make it easier to remove harmful content."Our actions and probably the passage ?of time have led to a significant reduction in online tension and risky situations," Tusk told a crisis meeting. "We will continue...