#369 Delete Xenforo (XF) encryption algorithm

Rationale:
- Seems not to have been working since it was added to the codebase
- Seems not to correspond to the actual Xenforo password hashing (class does some sort of JSON extraction?)
- It would be easier to rewrite it from scratch if someone requests it later

src/main/resources/config.yml

@@ -181,7 +181,7 @@ settings:
         # Example unLoggedinGroup: NotLogged
         unLoggedinGroup: unLoggedinGroup
         # possible values: MD5, SHA1, SHA256, WHIRLPOOL, XAUTH, MD5VB, PHPBB,
-        # MYBB, IPB3, PHPFUSION, SMF, XENFORO, SALTED2MD5, JOOMLA, BCRYPT, WBB3, SHA512,
+        # MYBB, IPB3, PHPFUSION, SMF, SALTED2MD5, JOOMLA, BCRYPT, WBB3, SHA512,
         # DOUBLEMD5, PBKDF2, PBKDF2DJANGO, WORDPRESS, ROYALAUTH, CUSTOM(for developpers only)
         passwordHash: SHA256
         # salt length for the SALTED2MD5 MD5(MD5(password)+salt)