move println!'s out of parse_dimac

rust/dpll/cnf.rs

                Ok(n) => { num_clauses = n }
                Err(e) => { return Err(format!("<num clauses> must be a positive integer: {}", e)) }
            }
            println!("cnf has {} variables and {} clauses", num_vars, num_clauses)
        }
    }
        }
        let l = vars.len();
        vars.truncate(l - 1);
        println!("{:?}", vars);
        clauses.push(vars)
    }
    let input: &mut String = &mut String::new();
    match io::stdin().read_to_string(input) {
        Ok(_) => match parse_dimac(input) {
            Ok(cnf) => { println!("ok!") }
            Ok(cnf) => {
                println!("cnf has {} variables and {} clauses", cnf.num_vars, cnf.num_clauses);
                for clause in cnf.clauses {
                    println!("{:?}", clause);
                }
            }
            Err(e) => { println!("Error: {}", e) }
        },
        Err(e) => { println!("Error: {}", e) }