rarfile v4.0

Main goals are:

• Increased zipfile-compatibility, thus also achieving smaller difference between RAR3 and RAR5 archives.
• Implement RarFile.extract on top of RarFile.open instead using unrar x directly, thus making maintenance of alternative backends more manageable. Negative aspect of that is that there are features that internal extract code does not support - hard links, NTFS streams and junctions.

Breaking changes:

• Directory names will have "/" appended. [#31]
• RarFile.extract operates only on single entry, so when used on directory it will create directory but not extract files under it.
• RarFile.extract/RarFile.extractall/RarFile.testrar will not launch special unrar command line, instead they are implemented on top of RarFile.open.
• Keyword args in top-level APIs were renamed to match zipfile:
  • RarFile(rarfile) -> RarFile(file)
  • RarFile.setpassword(password) -> .setpassword(pwd)
  • RarFile.getinfo(fname) -> .getinfo(name)
  • RarFile.open(fname, mode, psw) -> .open(name, mode, pwd)
  • RarFile.read(fname, psw) -> .read(name, pwd)
• PATH_SEP cannot be changed from "/".

New features:

• RarFile.extract will return final sanitized filename for target file. [#42, #52]
• RarInfo.is_dir is now preferred spelling of isdir(). Old method kept as alias. [#44]
• New RarInfo.is_file and RarInfo.is_symlink methods. Only one of ~RarInfo.is_file, ~RarInfo.is_dir or ~RarInfo.is_symlink can be True.
• RarFile.printdir has file argument for output.
• RarFile.__iter__ loops over RarInfo entries.
• RAR3: throw NeedFirstVolume exception with current volume number, like RAR5 does. [#58]
• Nanosecond timestamp support. Visible as nsdatetime instance.
• Minimal CLI when run as script: python3 -m rarfile
• Skip old file versions in versioned archive.

Cleanups:

• Use PBKDF2 implementation from hashlib.
• Improve test coverage.