Remove unreadPerCollection from the save and re-compute it directly in ImportFromLoreLibrary

Remove unreadPerCollection from the save and re-compute it directly in ImportFromLoreLibrary
Because the "read" flag was in the account wide save, if you read a book from one character, the count in the other character was wrong
Anyway, computing it in the ImportFromLoreLibrary has a very small impact performance wise and it avoid potential issues with the save

Remove local variables in ImportFromLoreLibrary as it wasn't compatible with addon overriding these functions (like LoreLibrary)