[FileComingOut] Added new line character management
[FileComingOut] Added new line character management

Trying to avoid using `explode` and `implode` directly with `PHP_EOL` as we
could have the following situation:

* a user is running on Windows (`PHP_EOL === "\r\n"`)
* he receives a file created on another OS (`new line character === "\n"`)

New line character detection should be done manually, in `Filesystem`. `File`
will only hold the value and use it internally.

pyrech-forks/redaktilo,pyrech-forks/redaktilo,gnugat/redaktilo,gnugat/redaktilo