The life and work of legendary film director Robert Altman will be celebrated at a symposium tonight at 5:30 PM, marking the publication of a new Altman biography and the 40th anniversary of his seminal film, “M*A*S*H.”  Favorite Altman actors Elliott Gould, Sally Kellerman, and Michael Murphy will be joined in a panel discussion by his widow, Kathryn Altman, Boston Globe film critic Ty Burr, and BU Prof essor Mitchell Zuckoff, author of “Robert Altman: The Oral Biography” (Knopf) followed by a screening of “M*A*S*H.” Open to the public ($10 for adults, $5 for children), the evening is sponsored by the BU College of Communication in concert with the BU Alumni Association’s Winterfest Weekend and co-sponsored by the College of Arts and Sciences Core Humanities.  It is taking place at the Tsai Performance Center (685 Commonwealth Avenue).