Tranform <br> to \n when using --text flag

Actual behaviour:

```shell
% echo '<div id="my-div">line1<br>line2<br>line3</div>' | htmlq -t "#my-div"
line1line2line3
```

Expected behaviour:

```shell
% echo '<div id="my-div">line1<br>line2<br>line3</div>' | htmlq -t "#my-div"
line1
line2
line3
```