ignore blank lines

It would be great if the tool ignored blank lines.

If you have a blank line in your `.env`, or more commonly just end the file with a newline, then the generated `.example` file has an extra `=` line.

.env
```
DB_TYPE=postgres
DB_USER=myapp

```

generated `.example` file
```
DB_TYPE=
DB_USER=
=
```

notice the last line with just a `=`