Separator

Interface:

public interface Separator {
    String pure();
    char charS();
    String regex();
    Separator mirror();
}

String pure() - basic separator.

char charS() - basic char separator.

String regex() - separator for using in regex.
```java 
Separator mirror() - Separator of another Os. Used to replace one separator with another.

SeparatorUnix - Separator for Unix-like OS.

SeparatorWin - Separator for Windows OS.

Separator used when growing a file tree, if need to use implementations to interact with filesystem.