Using her nervously flashing squinty-eyed smile and breathy, almost girlish speaking voice to great effect, character player Dianne Wiest has proven equally adept at portraying ditsy, somewhat neurotic comic characters, classically tragic figures and maternal authority figures. Attractive but not conventionally beautiful by Hollywood standards, this stage-trained performer has had only rare screen roles that allow her to unleash the full force of her capabilities. Nevertheless, she has emerged as an actress who commands respect and admiration--and along the way netted numerous accolades and