R.I.P Chris Burden, L.A.-based conceptual artist Chris Burden, 69, has died. “Chris Burden was extremely funny” (Gregory Jacobsen) .‘He was every inch an artist, as tough and uncompromising as any I have ever met,’ (art dealer Larry Gagosian) . . . “James Kalm picked up a copy of ARTFORUM Magazine and was transfixed. It was…