Rewrites encryption

Adds an optional real encryption mode, which encrypts pages using AES, without saving plaintext.
Re-implements the old magic encryption in non-real encryption mode.
Fixes incorrect key generation for use in the substitution cipher and the gene cipher.
Removes the option for saving books as txt.
Adds tests for all encryption methods.
Saves all necessary decryption data when storing encrypted books.
Removes the old book updating code.

src/main/resources/config.yml

@@ -1,8 +1,6 @@
 Options:
   # The language to use. Only "en" is built-in, but custom languages can be added
   Language: "en"
-  # Whether to use YAML for saved books instead of just storing them as text
-  Save_Books_in_Yaml_Format: true
   # The maximum number of duplicates of a saved book allowed
   Max_Number_of_Duplicates: 5
   # The separator used to separate the book title and the book author. While this is a ',' by default for backwards 
@@ -34,4 +32,8 @@ Options:
   #  vanilla behavior where a copy of a copy cannot be copied further.
   Change_Generation_On_Copy: false
   # Whether to enable hitting a chiseled bookshelf while sneaking to see the shelf's contents.
-  Enable_Book_Peeking: true
+  Enable_Book_Peeking: true
+  # Whether to use true AES encryption when encrypting and decrypting books. While the hashed password used for 
+  # encryption is still stored in the book file, the real contents of the book are not. Admin decrypt can be used to
+  # peek at books, if an admin gets a hold of one, but only the encrypted AES cypher text is stored in the book.
+  Use_Real_Encryption: false