Krista Brown '99 hopes one day to be a doctor, so perhaps it is appropriate that she has been busy this year making people feel better. The bio-chemistry student from Ketchum, Idaho, has delighted classmates and faculty with gifts of her impressionist paintings.     While she studied in the Colby in Dijon program last fall, Brown's paintings of provincial French scenes were so popular with friends that she decided to produce a 12-month calendar. When Director of Off-Campus Study Jon Weiss saw the calendar he agreed to pay for enough copies to give them as souvenirs to students and professors in the Dijon program.     Brown also painted a winter scene featuring Miller Library and Johnson Pond and an impressionist interpretation of Cotter Union.     Self-taught but interested in pursuing more formal training, Brown says she has been encouraged by her work with Assistant Professor of Art Bevin Engman. "I don't know a lot about technique; I just paint," Brown said. "I especially enjoy doing paintings for other people. It sort of inspires me."     She hasn't lost her desire to enter the medical field, says Brown, but she admits that "if I concentrated as hard on my bio-chem books as I do on my paintings, I'd have a better G.P.A."