Quote table and column names that contain special characters

This is necessary to generate valid SQL from NodeToString when table or column names contain special characters. I altered NodeToString by basically wrapping every call to `get<*>Name` with maybeQuote(...). An alternative strategy would be to implement quoting inside the `get<*>Name` functions, though this would change their existing behavior, and I'm not sure what the contract on these functions is intended to be.