Adds an option to only allow saving own books

src/main/resources/config.yml

@@ -23,6 +23,8 @@ Options:
   Author_Only_Copy: false
   # Whether to only allow the author of a book to unsign it
   Author_Only_Unsign: false
+  # Whether to only allow saving a player's own books with /savebook
+  Author_Only_Save: false
   # Whether to automatically format every book when it's signed
   Format_Book_After_Signing: false
   # Whether to display "COPY" or "COPY_OF_COPY" instead of "ORIGINAL" when a book is copied. This also uses the