Hundreds ofpro-Palestinian protesters, including parents with children atop their shoulders, streamed into Union Park on the third day of the Democratic National Convention, marking a stark contrast to violent clashes between police and protesters the night before that led to 56 arrests. Some played hacky sack Wednesday afternoon and others sat on the grass in the sun as protest leaders chanted, “The whole world is watching.” Raed Shuk, 48, brought his children from the suburbs, including his 2-year-old son. Shuk, whose parents are Palestinian, said they have come to so many rallies that his s…