Reading from stdin

Currently it's not possible to read from stdin:

```console
$ docker logs tasks 2>&1 | ./jlv -
Something went wrong: os: open -: no such file or directory.
```

A workaround is to use [bash process substitution](https://tldp.org/LDP/abs/html/process-sub.html):

```console
$ ./jlv <(docker logs tasks 2>&1)
```