`Position::line` reports inaccurate line following blank lines

#### What version of the `csv` crate are you using?

`1.1.3`

#### Briefly describe the question, bug or feature request.

`Reader` reasonably skips blank lines, and the reported position following them is largely still correct, except for the first record following the blank. The first record after a blank line reports the blank's line number rather than its own.

#### Include a complete program demonstrating a problem.

Rust program:

```rust
fn main() {
let mut rdr = csv::Reader::from_reader(std::io::stdin());
for result in rdr.records() {
let record = result.unwrap();

let expected: u64 = record.get(0).unwrap().parse().unwrap();
let actual = record.position().unwrap().line();

if expected != actual {
println!("expected: {}", expected);
println!("actual: {}", actual);
}
}
}
```

With CSV input:

```csv
line number
2

4
5
```

#### What is the observed behavior of the code above?

```
expected: 4
actual: 3
```

#### What is the expected or desired behavior of the code above?

No output.