By Tariq Naqash in the Dawn, Dec 27 MUZAFFARABAD, Dec 26: Activists of nationalist Kashmiri groups staged a demonstration here on Saturday to condemn the killing of a teenaged student and alleged rigging in a by-election in Gilgit-Baltistan. They warned the Pakistan People’s Party to desist from installing “puppet regime” in the region. The demonstration, organised by the Kashmir National Party (KNP), National Lawyers Forum (NLF), National Students Federation (NSF) and Balawaristan National Front (BNF),…