v0.4.0

- Use `%-s`, `%-q`, `%*-s`, `%*-q`, `%**-s`, `%**-q` syntax to read from stdin.
- Use `%(NAME@FILE)q` syntax to read default value from file.
- Use `%(NAME@-)q` syntax to read default value from stdin.
- Use `NAME@FILE` syntax to pass value for named placeholder from file.
- Use `NAME@-` syntax to pass value for named placeholder from stdin.
- Stdin values are separated by null (`\0`).

Examples:

```bash
seq 1 3 | xargs printf '%s\0' | jf '[%*-s]'

seq 1 3 | xargs printf '%s\0' | jf '{%q: %-s, %q: %(two)s, three: %(three@-)s}' one two two@-
```

Also, display better error for invalid expandable placeholder syntax.