Each time the judge strode into the court, the dark-haired defendant bowed respectfully in best Canadian courtroom tradition. Viola MacMillan, 63, has had occasion of late to learn about such legal amenities. A shrewd, if unlikely-looking prospector who amassed a fortune in sundry Canadian mining ventures, tiny (5 ft., 100 Ibs.) Viola has been under government investigation ever since a mercurial trading binge on the Toronto Stock Exchange in 1964 left investors in her Windfall Oils & Mines Ltd. holding an empty sack. Called "the Queen Bee" by mining men, who elected her president of the Prospectors and Developers Association...