“Slings & Arrows’” second season revisits the comically dysfunctional New Burbage Theater Festival, under the artistic direction of Geoffrey Tennant (Paul Gross). Tennant’s triumph with “Hamlet” has done nothing to solve the theater’s financial woes, and now he has no choice but to mount a new production of the most jinxed play in theatrical history: “Macbeth.” Ellen’s boyfriend also proposes to her, but thanks to Geoffrey’s interference, she declines.