“On Wednesday night, a semi-staged ‘Merrily’ was presented at New York’s City Center, placing the problematic show closer to Broadway both in spirit and location — only four blocks from its original theater — than it’s been in 30-plus years. How did ‘Merrily’ get here after all its drama — it was the ‘Spider-Man’ of its season, with postponements, creative replacements and plenty of ill will — and after all these years?”