Allow custom memorization content

[LorenDB]

Users should be able to memorize their own custom content (e.g. poems). This is actually going to be a pretty large project, because it might be good to use this as an opportunity to relegate the Bible functions to a submodule/one of several functions of the program. At the same time, it might be a good idea to add the capability to save content, because users aren't going to want to have to enter their custom content every time they start the program.